There is no answer to this.
It sounds like your TV has a USB input, but without knowing more about the TV it's impossible to say what you need to do to get your presentation to play on the TV via USB.
I'll go out on a limb and say there's about a 0% chance that your TV can play Keynote presentations directly. Off-hand, I don't know any that can.
It may be that your TV will recognize a USB drive with a series of JPG images on it, and will show a slideshow of those images, in which case exporting your presentation to JPGs and storing them on the drive may be enough.
However, there are a million and one gotchas with that. Different brands (and even models) of TV have different rules - some will play images on the top level of the USB drive. Others want specific named folders to display. Others will let you choose.
So without more details it's impossible to tell you precisely what you need to do.
The easier solution, if I dare to say, is to hook your computer to the TV via HDMI (assuming it has an HDMI interface), and just using it as an external display, which will let you run the presentation directly, ignoring the USB port altogether.