SELECT 
  product_id, 
  short_description, 
  full_description 
FROM 
  cscart_product_descriptions 
WHERE 
  product_id IN (
    13825, 13686, 12667, 12678, 12672, 12671
  ) 
  AND lang_code = 'en'

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "4.21"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 6,
      "rows_produced_per_join": 6,
      "filtered": "100.00",
      "index_condition": "((`dev_yourmart_co_bw`.`cscart_product_descriptions`.`product_id` in (13825,13686,12667,12678,12672,12671)) and (`dev_yourmart_co_bw`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "3.61",
        "eval_cost": "0.60",
        "prefix_cost": "4.21",
        "data_read_per_join": "22K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ]
    }
  }
}