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 (
    97669, 97670, 97671, 97672, 97673, 97674, 
    97675, 97676, 97677, 97678, 97679, 
    97680, 97681, 97682, 97683, 97684, 
    97685, 97686, 97687, 97688, 97689, 
    97690, 97691, 97692, 97693, 97694, 
    97695, 97696, 97697, 97698
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00072

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 (97669,97670,97671,97672,97673,97674,97675,97676,97677,97678,97679,97680,97681,97682,97683,97684,97685,97686,97687,97688,97689,97690,97691,97692,97693,97694,97695,97696,97697,97698)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}