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 (
    96918, 96919, 96985, 96986, 96987, 96988, 
    96989, 96990, 96991, 96992, 96993, 
    96994, 96995, 96996, 96997, 96998, 
    96999, 97000, 97001, 97002, 97003, 
    97004, 97005, 97006, 97007, 97008, 
    97009, 97010, 97083, 97219
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00066

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 (96918,96919,96985,96986,96987,96988,96989,96990,96991,96992,96993,96994,96995,96996,96997,96998,96999,97000,97001,97002,97003,97004,97005,97006,97007,97008,97009,97010,97083,97219)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}