I think there are just too many variables to say what would be a safe time limit for the age of a belt. May also be why my Honda shop manual gives no combined distance / time limit, only distance. That maximum service interval is every 144k km.
It does recommend periodic belt inspections every 96k km. That is not hard to do and doesn't require any parts replacement. Look at the condition of your belt and check it for cracks and fraying on both sides using a very bright flashlight.
Also consider that the cost of having a belt fail is an order of magnitude above what it costs to have it replaced. An old belt really should be replaced. There are other things beside the belt in there that should be looked at too, irregardless of age and a belt made of rubber and kevlar do have a life, after all. I'd bite the bullet and replace that belt. It will allow you to fully inspect that part of the engine, (idler bearings and water pump). If you're questioning the condition of your belt, it will bring you piece of mind knowing it's replaced.
Ross