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 (
    88502, 90836, 87505, 87521, 88454, 88471, 
    88487, 89021, 87537, 88422, 89839, 
    89891, 89963, 88523, 85722, 85739, 
    85749, 85759, 88193, 88205, 88980, 
    88997, 88495, 85719, 87506, 87522, 
    88453, 88470, 88486, 89837
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00092

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (88502,90836,87505,87521,88454,88471,88487,89021,87537,88422,89839,89891,89963,88523,85722,85739,85749,85759,88193,88205,88980,88997,88495,85719,87506,87522,88453,88470,88486,89837)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}