SELECT 
  q_product_descriptions.product_id, 
  q_product_descriptions.short_description, 
  IF(
    q_product_descriptions.short_description = '', 
    q_product_descriptions.full_description, 
    ''
  ) AS full_description 
FROM 
  q_product_descriptions 
WHERE 
  q_product_descriptions.product_id IN (
    5878, 5879, 5880, 5881, 5882, 5883, 5884, 
    5885, 5886, 5887, 5888, 5889, 5890, 
    5891, 5892, 5893, 5894, 5895, 5896
  ) 
  AND q_product_descriptions.lang_code = 'en'

Query time 0.00054

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "45.61"
    },
    "table": {
      "table_name": "q_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": 19,
      "rows_produced_per_join": 19,
      "filtered": "100.00",
      "index_condition": "((`portal`.`q_product_descriptions`.`product_id` in (5878,5879,5880,5881,5882,5883,5884,5885,5886,5887,5888,5889,5890,5891,5892,5893,5894,5895,5896)) and (`portal`.`q_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "41.81",
        "eval_cost": "3.80",
        "prefix_cost": "45.61",
        "data_read_per_join": "72K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ]
    }
  }
}