SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    99105, 99106, 99107, 99108, 99109, 99114, 
    99136, 99137, 99138, 99139, 99140, 
    99145, 99146, 99147, 99148, 99149, 
    99150, 99153, 99154, 99155, 99156, 
    99157, 99158, 99159, 99160, 99161, 
    99167, 99181, 99185, 99186
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "table": {
      "table_name": "cscart_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",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (99105,99106,99107,99108,99109,99114,99136,99137,99138,99139,99140,99145,99146,99147,99148,99149,99150,99153,99154,99155,99156,99157,99158,99159,99160,99161,99167,99181,99185,99186)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}