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 (
    94956, 94957, 95655, 95656, 95657, 95658, 
    95659, 95660, 96698, 96699, 96700, 
    96701, 96702, 96703, 96704, 96705, 
    101036
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00066

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "7.66"
    },
    "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": 17,
      "rows_produced_per_join": 17,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "5.97",
        "eval_cost": "1.70",
        "prefix_cost": "7.67",
        "data_read_per_join": "64K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (94956,94957,95655,95656,95657,95658,95659,95660,96698,96699,96700,96701,96702,96703,96704,96705,101036)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}