Yeah, 5 sets of 3 reps at your working weight, I'd focus on your squat for core strengthening, nice steady controlled speed down and up, perfect form. Doesn't have to be anything mad - a couple of times a week and you'll notice an increase in strength. 5 mins on rower to warm up, then start empty bar (x10 reps) and work up through the plates (x5 reps) to your working weight. If you're squatting around your bodyweight you can be in and out in half hour. Job done.
Depending on your body and your other training you might see a bit of quad and glute growth after a several months, but certainly not going to be putting on the mass you're worried about.