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 (
    296840, 296925, 296815, 296844, 296874, 
    296922, 296924, 296843, 296902, 296891, 
    296863, 296923, 296850, 296916, 296813, 
    296856, 296854, 296901, 296878, 296871, 
    296867, 296879, 296918, 296870
  ) 
  AND product_descriptions.lang_code = 'en'

Query time 0.00113

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "20.34"
    },
    "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": "17.95",
        "eval_cost": "2.40",
        "prefix_cost": "20.35",
        "data_read_per_join": "122K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`goimagine`.`product_descriptions`.`product_id` in (296840,296925,296815,296844,296874,296922,296924,296843,296902,296891,296863,296923,296850,296916,296813,296856,296854,296901,296878,296871,296867,296879,296918,296870)) and (`goimagine`.`product_descriptions`.`lang_code` = 'en'))"
    }
  }
}