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 (
    55853, 85838, 55857, 70639, 67652, 55856, 
    84572, 108231, 66650, 85837, 70643, 
    84570, 50164, 71650, 70642, 50165, 
    67651, 108235, 108236, 230438, 230436, 
    249322, 250146, 250148
  ) 
  AND product_descriptions.lang_code = 'en'

Query time 0.00444

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "20.02"
    },
    "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": "17.62",
        "eval_cost": "2.40",
        "prefix_cost": "20.02",
        "data_read_per_join": "122K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`goimagine`.`product_descriptions`.`product_id` in (55853,85838,55857,70639,67652,55856,84572,108231,66650,85837,70643,84570,50164,71650,70642,50165,67651,108235,108236,230438,230436,249322,250146,250148)) and (`goimagine`.`product_descriptions`.`lang_code` = 'en'))"
    }
  }
}