SELECT 
  cscart_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      cscart_products_categories.link_type = "M", 
      CONCAT(
        cscart_products_categories.category_id, 
        "M"
      ), 
      cscart_products_categories.category_id
    )
  ) AS category_ids, 
  product_position_source.position AS position 
FROM 
  cscart_products_categories 
  INNER JOIN cscart_categories ON cscart_categories.category_id = cscart_products_categories.category_id 
  AND cscart_categories.storefront_id IN (0, 1) 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  LEFT JOIN cscart_products_categories AS product_position_source ON cscart_products_categories.product_id = product_position_source.product_id 
  AND product_position_source.category_id = 512 
WHERE 
  cscart_products_categories.product_id IN (
    12498, 15432, 3317, 3314, 3319, 3316, 
    3320, 3318, 3315, 3321, 3322, 3298, 
    3299, 3329, 3330, 3306, 3305, 3304, 
    3325, 3289, 3287, 3283, 3284, 3285, 
    3286, 3292, 3291, 3300, 3301, 3302, 
    3326, 3295, 3294, 3327, 3297, 3307, 
    3309, 3308, 3293, 3288, 3290, 3303, 
    3310, 3324, 3323, 13136, 3922, 15904
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00172

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "68.36"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "range",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "pt",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "rows_examined_per_scan": 49,
            "rows_produced_per_join": 49,
            "filtered": "100.00",
            "index_condition": "(`dev_yourmart_co_bw`.`cscart_products_categories`.`product_id` in (12498,15432,3317,3314,3319,3316,3320,3318,3315,3321,3322,3298,3299,3329,3330,3306,3305,3304,3325,3289,3287,3283,3284,3285,3286,3292,3291,3300,3301,3302,3326,3295,3294,3327,3297,3307,3309,3308,3293,3288,3290,3303,3310,3324,3323,13136,3922,15904))",
            "cost_info": {
              "read_cost": "29.16",
              "eval_cost": "4.90",
              "prefix_cost": "34.06",
              "data_read_per_join": "784"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "table": {
            "table_name": "product_position_source",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id",
              "product_id"
            ],
            "key_length": "6",
            "ref": [
              "const",
              "dev_yourmart_co_bw.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 49,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "12.25",
              "eval_cost": "4.90",
              "prefix_cost": "51.21",
              "data_read_per_join": "784"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        },
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "dev_yourmart_co_bw.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 2,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "12.25",
              "eval_cost": "0.25",
              "prefix_cost": "68.36",
              "data_read_per_join": "6K"
            },
            "used_columns": [
              "category_id",
              "usergroup_ids",
              "status",
              "storefront_id"
            ],
            "attached_condition": "((`dev_yourmart_co_bw`.`cscart_categories`.`storefront_id` in (0,1)) and ((`dev_yourmart_co_bw`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`dev_yourmart_co_bw`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`dev_yourmart_co_bw`.`cscart_categories`.`usergroup_ids`))) and (`dev_yourmart_co_bw`.`cscart_categories`.`status` in ('A','H')))"
          }
        }
      ]
    }
  }
}