SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39db89eae87b52ff0ef95a4a03a809a3ef042f0f8a57e668587229caf372066c' 
  AND token = 'ZsKYb9bzj1QbzRiJpqFUe9gnJkwGV+OoJPxU3LjC/+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00088

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}