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 (
    94690, 94692, 94693, 94710, 94714, 94716, 
    96302, 96303, 96712, 96716, 96721, 
    96729, 96730, 96731, 96736, 96737, 
    96750, 96753, 96754, 96768, 96769, 
    96788, 97012, 97020, 97036, 97043, 
    97049, 97051, 97055, 97810
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00075

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 (94690,94692,94693,94710,94714,94716,96302,96303,96712,96716,96721,96729,96730,96731,96736,96737,96750,96753,96754,96768,96769,96788,97012,97020,97036,97043,97049,97051,97055,97810)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}