It probably won't burn up.
If you think it has made it to your cylinder, you can try removing the plug, and fishing it out with some tape on the end of a wire. Or by blowing compressed air into the injector opening with the intake valve in the open position and the spark plug removed. This should blast out any debris in your intake tract.
If you think it is just in the intake runner of your manifold or head, you can pull your manifold off.
If the piece is small, you could just "run it" and blow it out. Thats up to you. I don't think a small piece of plastic is going to damage your engine. If it does get stuck, you should know pretty quick. Your course would be clear then.