Get the heat rock OUT. If you want a burned snake, go ahead and keep it in. Also, if heat rocks get wet, your snake may get electrocuted. Untreated burns lead to bacterial infections, ex. scalerot, which can then lead to full-blown septicemia(bacteria in the blood), and that will lead to death very quickly.
Your snake needs a proper environment to thrive, not just survive, in your care. We have a wonderful caresheet here, make yourself familiar with it, for your snake's well-being.