Qatar Airways only requires payment verification for selected booking. If your transaction is flagged for verification, you will receive an email to the address you used at the time of payment. This email contains your customised verification link, which you can use to confirm your payment.
If you did not recieve such an email, you will not have to present the payment card during your trip. To check whether you need to verify your payment or not, please retrieve your booking through 'Manage Booking' or contact the nearest Qatar Airways office.