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 (
    97807, 97808, 97809, 98590, 98591, 98592, 
    98593, 98594, 98595, 98596, 98597, 
    98598, 98599, 98604, 98605, 98614, 
    98615, 98617, 98618, 98619, 98620, 
    98621, 98622, 98623, 98624, 98651, 
    98681, 98760, 98761, 99012
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00031

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 (97807,97808,97809,98590,98591,98592,98593,98594,98595,98596,98597,98598,98599,98604,98605,98614,98615,98617,98618,98619,98620,98621,98622,98623,98624,98651,98681,98760,98761,99012)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}