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 (
    90108, 89006, 89013, 84007, 84009, 84011, 
    84013, 89010, 91307, 83963, 83965, 
    83967, 83969, 91303, 83130, 84006, 
    84008, 84010, 84012, 84035, 90089, 
    90099, 92027, 92028, 92029, 92030, 
    92031, 92032, 92033, 92035
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00114

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 (90108,89006,89013,84007,84009,84011,84013,89010,91307,83963,83965,83967,83969,91303,83130,84006,84008,84010,84012,84035,90089,90099,92027,92028,92029,92030,92031,92032,92033,92035)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}