NoStressHere Since you are in transit you are already checked-in. If you already have your onward boarding pass then you may exit the airport and upon return go straight to immigration, security etc. bypassing check-in. It is only the check-in process that starts 3 hours before departure and you are already checked-in so you can return to the departure lounge at any time prior to your flight. Should you have baggage to check-in do so at your origin airport all the way through to your final destination.
I am sure that there are members of this forum that can give you further advice