SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    391, 505, 474, 566, 567, 568, 569, 570, 
    571, 572, 573, 574, 576
  ) 
  AND category_id != 264

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "9.11"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "parent",
        "p_category_id"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 13,
      "rows_produced_per_join": 12,
      "filtered": "99.34",
      "index_condition": "(`dev_yourmart_co_bw`.`cscart_categories`.`parent_id` in (391,505,474,566,567,568,569,570,571,572,573,574,576))",
      "cost_info": {
        "read_cost": "7.82",
        "eval_cost": "1.29",
        "prefix_cost": "9.11",
        "data_read_per_join": "34K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`dev_yourmart_co_bw`.`cscart_categories`.`category_id` <> 264)"
    }
  }
}