Unfortunately, there is no way–including visual inspection–to predict when a timing belt will snap, and that is why it is prudent to change them on schedule. “On schedule” for a modern car usually means every 105k miles or 8 years, whichever comes first. However, it is possible that a car of 2002 vintage might call for replacement earlier, at–perhaps–80k miles or 5 years. What does your Owner’s Manual have to say regarding the interval for this maintenance?
Apparently, you bought a car that did not come with maintenance records, and therein lies the problem. Unless you know, through hard copy records, that the timing belt was replaced within the past few years, then you would be very foolish to trust that the previous owner may have replaced it. That might be a gamble that some people are willing to take, but I am not one of those people, and I would advise you to have the job done a.s.a.p. Make sure that your mechanic also replaces the water pump, serpentine belt, and all belt tensioners.
And, the next time that you are in the market for a used car, I suggest that you limit yourself to those that come with full maintenance records that you can compare (at your leisure) to the mfr’s maintenance schedule. Taking that extra step allows you to weed-out cars that have not been maintained properly, and to save yourself the expense of added maintenance and (probably) higher repair costs in the long run.