Unless you ruin your honey, and 140 degrees Celsius for one hour would certainly do that!
But there again, a water bath will never go over 100 C!
There is no temperature one should heat to to prevent it crystallising. All honey will granulate, sooner or later.
Well filtered (the finer the retained particles) will slow the granulation (fewer and finer particles to start the crystal growth process).
Some honey may well granulate very quickly - OSR is one - and might be done as soft set. Some, borage for eg, seems to stay liquid for a long time, but will granulate eventually.
Granulation rate may also be a function of water content.
Some customers ask for runny honey.
If it is going to be used right away, warming to liquify just before use, might be the answer. If it is a retail outlet, you may be in trouble!
There are granulation labels available as instruction for end-users who require runny hunny.
Repeated or prolonged over-heating of honey is not recommended as good practice and may cause legal bother if found to be outside the limits for Hydroxymethylfurfural (HMF). But if liquifying honey it must be completely liquified or it will re-granulate quickly, dependent on storage conditions, of course.
Not a lot of help, methinks. But may be of some use!
Regards, RAB