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 (
    8790, 8791, 8792, 9050, 9052, 9053, 9054, 
    9055, 9056, 9057, 9058, 9817, 9818, 
    9819, 9820, 9821, 9822, 9823, 9824, 
    9825, 9826, 9827, 9828, 9829, 9830, 
    9831, 9832, 9833, 9834, 9835
  ) 
  AND q_product_descriptions.lang_code = 'en'

Query time 0.00064

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "72.01"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "index_condition": "((`portal`.`q_product_descriptions`.`product_id` in (8790,8791,8792,9050,9052,9053,9054,9055,9056,9057,9058,9817,9818,9819,9820,9821,9822,9823,9824,9825,9826,9827,9828,9829,9830,9831,9832,9833,9834,9835)) and (`portal`.`q_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "66.01",
        "eval_cost": "6.00",
        "prefix_cost": "72.01",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ]
    }
  }
}