SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '829e72cb861014b41f95fc8983ac26c32a34793133016281ddc6331acab2567e' 
  AND token = '5NHUQ1lnuTbpVnVXweRtpgsWokZLkiRlZVwFQS+/zK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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