our company has a few products available: an acrylic and a water based epoxy. Any application will be best over bare, clean concrete, however both can be applied to soundly adhering paints. Any remaining paint should be abraded to provide tooth.
Prior to considering a floor coating, you should perform a moisture content test: duct tape a 3' X 3' sheet of plastic to the floor for 24 hours. If there is water on the sheet when it is removed then you should not put an epoxy or oil based product on the floor. The ground moisture will cause failure. Use the acrylic.