Cristina, can you run a bar through or in front of the door? Can you mill slots for ratchet locks on top or bottom?
Personally, I would not worry too much about high security if you are going to leave the stuff in that kind of cabinet. Breaking or cutting the glass or the door would be much easier than worrying about the locks. A keypad connected to absolutely nothing except maybe to a LED or 2 and some great acting will be a better deterent to an unsophisticated thief and maybe a challenge to a good one.