Do you mean literally afk or just going around in a specified area?

 

Code (Text):

1. every 1 minute:
2.     if "%region at player%" is "region name":
3.         do your thing

If you want to check your region name you can put in the every 1 minute loop
broadcast "%region at player%" while you are standing in the region

This is a simple way but it has flaws, which is if he leaves and come back before the 1 min, it will still reward him, instead just make a counter to fix that

something like that

Code (Text):

1. every 1 second:
2.     loop all players:
3.         if {counter.%loop-player's uuid%} is not set:
4.             set {counter.%loop-player's uuid%} to 0
5.         if "%region at loop-player%" is "lowlyzombies in world world":
6.             add 1 to {counter.%loop-player's uuid%}
7.             if {counter.%loop-player's uuid%}>= 60:
8.                 set {counter.%loop-player's uuid%} to 0
9.                 send "hi" to loop-player
10.         else:
11.             set {counter.%loop-player's uuid%} to 0
12.