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 (
    99111, 99122, 99124, 99126, 99129, 99163, 
    99172, 99178, 99184, 99204, 99207, 
    99223, 99224, 99225, 99226, 99228, 
    99229, 99244, 99253, 99260, 99271, 
    99280, 99281, 100388, 100389, 100432, 
    100671, 100672, 100673
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00087

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.07"
    },
    "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": 29,
      "rows_produced_per_join": 29,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.17",
        "eval_cost": "2.90",
        "prefix_cost": "13.07",
        "data_read_per_join": "110K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (99111,99122,99124,99126,99129,99163,99172,99178,99184,99204,99207,99223,99224,99225,99226,99228,99229,99244,99253,99260,99271,99280,99281,100388,100389,100432,100671,100672,100673)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}