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 (
    101516, 101525, 101534, 101554, 101563, 
    101572, 101814, 101815, 101816, 101817, 
    101818, 101819, 101820, 101821, 101822, 
    101823, 101834, 101835, 101836, 101837, 
    101838, 101839, 101840, 101841, 101842, 
    101843
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00070

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "11.72"
    },
    "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": 26,
      "rows_produced_per_join": 26,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "9.12",
        "eval_cost": "2.60",
        "prefix_cost": "11.72",
        "data_read_per_join": "99K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (101516,101525,101534,101554,101563,101572,101814,101815,101816,101817,101818,101819,101820,101821,101822,101823,101834,101835,101836,101837,101838,101839,101840,101841,101842,101843)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}