To the OP, ignore the guys having fun with it, please, most of them live in areas where you have the right to defend yourself and your property, I realize that is not an option for you. And the 'set gun' approach to booby trapping is unlawful anywhere in the US, so the guys again are having some fun.
So ignoring the fun though unlawful things, There are some ways to keep your tools more safe but really, we would need more information.
If the boxes are not really high end i.e. SnapOn, Lista, Vidmar, Matco, Mac, then the locks are probably useless, so you would need to cover the boxes. My first thought would be a wrought iron cage with the boxes inside, that after you secure the boxes you lock the cage. Shouldn't cost more than one single box does new, and probably less.
Cheaper but commonly used method is chain link cage.
Boxes can be very tightly locked with 1/4 by 2 inch metal bars strategically welded and locked in place over the drawers. I've seen that in garages in the bad parts of town.
On general theft, again it depends on your thief and neighborhood.
Common thieves like teens looking for pawn-able stuff for drugs/pocket money, lights and high visibility does the trick.
On the cheap, get some motion detector lights and position them inside the shop, the dual head light, about 15 dollars locally, with one head a bright light, the other with a cord going to a 'noise maker' some simple but LOUD siren etc.
A pro is going to get to your tools, but really, how many professional thieves target small shops?
