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 (
    89982, 89983, 89984, 87620, 87622, 84702, 
    84705, 91052, 88545, 88046, 88403, 
    84697, 84698, 88140, 88143, 88508, 
    88543, 88765, 89016, 88566, 87617, 
    87625, 87890, 88673, 88720, 88401, 
    84695, 88937, 87877, 88045, 88565, 
    88564, 87636, 88515, 88518, 89107, 
    89114, 88514, 88517, 90832, 88511, 
    87621, 87623, 88083, 88671, 88718, 
    87635, 87638
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00099

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 (89982,89983,89984,87620,87622,84702,84705,91052,88545,88046,88403,84697,84698,88140,88143,88508,88543,88765,89016,88566,87617,87625,87890,88673,88720,88401,84695,88937,87877,88045,88565,88564,87636,88515,88518,89107,89114,88514,88517,90832,88511,87621,87623,88083,88671,88718,87635,87638)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}