My cat scratched his eye, now has a white bump. Is it an infection? What should I do?

That is an odd bump on Moteur. I think a warm compress twice daily is a good idea. It may be something like a minor infection or perhaps a fluid filled cyst. Make sure to protect it from Moteur scratching at it (make him wear an elizabethan collar if you need to). Given that its so close to his eye, I would be hesitant to try to apply any ointment as I fear he would move and end up getting something in the eye.
If that lesion starts to swell, look inflamed, ruptures, or is still there in a month, then I think you should have him examined by his veterinarian. Although it does not look like it is connected to his actual eye, monitor that as well for redness, squinting or excessive tearing.
I hope this helps and hopefully that goes away quickly! Please feel free to post any additional questions.