Have a look at the GD 400 and GD 500 These work with a steel casting set in concrete at the threshhold centre. The angle bracket shown is bolted to the door and a hefty locking pin drops down through the angle plate and becomes unwithdrawable with a separate key.
click here I had one the 500 which was overkill and my son bought a smaller 400.
There is asolutely no way to force the lock and even a tinny up and over door would have to be cut all round the bolt to open up.
If you're garage has a separate personnel access, a simpler and cheaper option is an internal pair of hasps with quality padlocks inside. The downside of an obviously super secure garage lock, is it says "break into me, I've got valuables in the garage".
The Pacri locks are fitted near the bottom of the door on either side. They require 3 holes drilling through the door for each lock, 2 for the blind bolts and one for the keyhole. There's a cover plate for the keyhole to tidy it up. You then need to drill a deep hole into each side of the door frame to line up where the bolts slide in.
I'm fairly ham-fisted but have managed to install them neatly. I did have to borrow a drill though as the bit required to drill the holes in the frame are quite a large diameter.
They've been on my garage door since 1991 with no signs of rusting or other deterioration.
They're not very visible from a distance either. If you're interested I'll take a photo.