is there any way to use buttons for opening and closing with specific time period

I am going to develop cinema ticketing software I use QR code on tickets for authentication. now i wanna scan tickets only for current show for example show time 11 to 12, 1, 2 and 3 to 4. just current shows tickets should be scanned before and after 15 minutes. how can I achieve this using c# asp. net web forms