I have a cheap retractable cable lock that I use for short stops like that (if I lock it at all ... depends on where I am).

You could probably cut my lock with scissors, but the point is just to discourage opportunists. A serious thief is going to get any bike they want, or at least parts of it.

When I ride to work (not often) I bring the bike inside. I wouldn't be so shy of leaving it outside if the bike racks were in view of the security cameras ... I've asked several times for the racks to be moved or the cameras to be zoomed out, but no dice.