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 (
    98579, 98580, 98581, 98582, 98583, 98584, 
    98585, 98586, 98687, 98688, 98689, 
    98690, 98691, 98692, 98693, 98694, 
    98695, 98696, 98697, 98698, 98699, 
    98700, 98701, 98702
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00110

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 (98579,98580,98581,98582,98583,98584,98585,98586,98687,98688,98689,98690,98691,98692,98693,98694,98695,98696,98697,98698,98699,98700,98701,98702)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
98579
98580
98581
98582
98583
98584
98585
98586
98687
98688
98689
98690
98691
98692
98693
98694
98695
98696
98697
98698
98699
98700
98701
98702