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 (
    98215, 98216, 98217, 98218, 98219, 98220, 
    98221, 98222, 98223, 98322, 98323, 
    98482, 98509, 98510, 98511, 98512, 
    98513, 98514, 98516, 98517, 98518, 
    98519, 98520, 98538
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00070

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.44"
    },
    "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": 24,
      "rows_produced_per_join": 24,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "11.04",
        "eval_cost": "2.40",
        "prefix_cost": "13.44",
        "data_read_per_join": "91K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (98215,98216,98217,98218,98219,98220,98221,98222,98223,98322,98323,98482,98509,98510,98511,98512,98513,98514,98516,98517,98518,98519,98520,98538)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
98215
98216
98217
98218
98219
98220
98221
98222
98223
98322
98323
98482
98509
98510
98511
98512
98513
98514
98516
98517
98518
98519
98520
98538