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 (
    96959, 96960, 96961, 96962, 96963, 96964, 
    96965, 96966, 96967, 96968, 96969, 
    96970, 96971, 96972, 96973, 96974, 
    96975, 96976, 96977, 96978, 96979, 
    96980, 96981, 96982, 96983, 96984, 
    96998, 98192, 98193, 98194
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00069

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 (96959,96960,96961,96962,96963,96964,96965,96966,96967,96968,96969,96970,96971,96972,96973,96974,96975,96976,96977,96978,96979,96980,96981,96982,96983,96984,96998,98192,98193,98194)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}