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 (
    84706, 91053, 88941, 88512, 88141, 88144, 
    88939, 90126, 90129, 84702, 84705, 
    91052, 84697, 84698, 88946, 88947, 
    88948, 88140, 88143, 88508, 87890, 
    88943, 88944, 88945, 84695, 88937, 
    87877, 90124, 90125, 90127, 90128, 
    88515, 88518, 87282, 87290, 88514, 
    88517, 88511, 87876, 88506, 88507, 
    88510, 90828, 90827, 87995, 87882, 
    86861, 87875
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00086

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "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": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (84706,91053,88941,88512,88141,88144,88939,90126,90129,84702,84705,91052,84697,84698,88946,88947,88948,88140,88143,88508,87890,88943,88944,88945,84695,88937,87877,90124,90125,90127,90128,88515,88518,87282,87290,88514,88517,88511,87876,88506,88507,88510,90828,90827,87995,87882,86861,87875)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}