SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    270188, 285000, 387031, 387032, 387087, 
    387033, 387020, 387035, 387025, 387024, 
    387034, 387026, 387030, 387021, 387027, 
    387023, 387019, 387028, 387022, 387036, 
    387029
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00135

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "29.44"
    },
    "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": 21,
      "rows_produced_per_join": 21,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "25.25",
        "eval_cost": "4.20",
        "prefix_cost": "29.45",
        "data_read_per_join": "143K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_descriptions`.`product_id` in (270188,285000,387031,387032,387087,387033,387020,387035,387025,387024,387034,387026,387030,387021,387027,387023,387019,387028,387022,387036,387029)) and (`webmarco`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}