If the lock was OEM, a key code might be on a info placard, usually in the trunk. Any Suzuki or GM dealer should be able to cut a key from the code.
You could always have a locksmith open it up.
several years ago, we bought a used geo tracker. spare tire had a cover on it. I now found out the tire has a lock on it. Obviously we have no key. Any suggestions on how to find a key, other suggestions? It's totally useless as is.