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 (
    91298, 83106, 91305, 84112, 89488, 91306, 
    91301, 83112, 83122, 83132, 89624, 
    90066, 86384, 89618, 89631, 89625, 
    89638, 89634, 89726, 90091, 90101, 
    90078, 85533, 89015, 90072, 84108, 
    89621, 83102, 89622, 89635, 90086, 
    90088, 90098, 83129, 90085, 92018, 
    92106, 89012, 91302, 86382, 89192, 
    92003, 92004, 92005, 92006, 92007, 
    92008, 92009
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00046

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 (91298,83106,91305,84112,89488,91306,91301,83112,83122,83132,89624,90066,86384,89618,89631,89625,89638,89634,89726,90091,90101,90078,85533,89015,90072,84108,89621,83102,89622,89635,90086,90088,90098,83129,90085,92018,92106,89012,91302,86382,89192,92003,92004,92005,92006,92007,92008,92009)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}