SELECT 
  product_descriptions.product_id, 
  product_descriptions.short_description, 
  IF(
    product_descriptions.short_description = '' 
    OR product_descriptions.short_description IS NULL, 
    product_descriptions.full_description, 
    ''
  ) AS full_description 
FROM 
  product_descriptions 
WHERE 
  product_descriptions.product_id IN (
    468398, 468399, 468909, 468929, 468930, 
    468932, 468940, 468943, 468948, 468949, 
    468956, 468964, 469661, 469667, 469722, 
    469723, 469724, 470225, 470233, 470234, 
    470237, 470245, 470251, 470259
  ) 
  AND product_descriptions.lang_code = 'en'

Query time 0.00094

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "20.16"
    },
    "table": {
      "table_name": "product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "11",
      "rows_examined_per_scan": 24,
      "rows_produced_per_join": 24,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "17.76",
        "eval_cost": "2.40",
        "prefix_cost": "20.16",
        "data_read_per_join": "122K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`goimagine`.`product_descriptions`.`product_id` in (468398,468399,468909,468929,468930,468932,468940,468943,468948,468949,468956,468964,469661,469667,469722,469723,469724,470225,470233,470234,470237,470245,470251,470259)) and (`goimagine`.`product_descriptions`.`lang_code` = 'en'))"
    }
  }
}