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 (
    9623, 9639, 9640, 9641, 9642, 9643, 9647, 
    9656, 9659, 9660, 9661, 9662, 9663, 
    9664, 9665, 9675, 9676, 9677, 9678, 
    9679, 9686, 9687, 9688, 9689, 9690, 
    9691, 9692, 9696, 9697, 9698, 9699, 
    9700
  ) 
  AND q_product_descriptions.lang_code = 'en'

Query time 0.00074

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "76.81"
    },
    "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": 32,
      "rows_produced_per_join": 32,
      "filtered": "100.00",
      "index_condition": "((`portal`.`q_product_descriptions`.`product_id` in (9623,9639,9640,9641,9642,9643,9647,9656,9659,9660,9661,9662,9663,9664,9665,9675,9676,9677,9678,9679,9686,9687,9688,9689,9690,9691,9692,9696,9697,9698,9699,9700)) and (`portal`.`q_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "70.41",
        "eval_cost": "6.40",
        "prefix_cost": "76.81",
        "data_read_per_join": "122K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ]
    }
  }
}