In a smoky indoor environment, the main practical precautions are to use well-sealed gear if you have it and avoid changing lenses while shooting. Higher-end DSLR bodies and lenses often have dust/weather sealing around buttons and controls, which helps reduce the amount of airborne contamination getting inside.

A zoom lens that extends may move some air, but the simplest way to limit risk is to keep one lens mounted for the session rather than swapping lenses in the smoke. That will do more to protect the sensor and mirror box than anything else.

If you need maximum protection, a full enclosure such as an underwater-style housing or protective cover would isolate the camera almost completely, but that’s usually excessive for a bar project.

So, for most situations: use the best-sealed body/lens available, keep the camera closed up, and don’t change lenses in the smoky environment.