My tap hot water comes out between 125 to 130 depending on water usage so that's plenty hot for my towels.

Quote from the American Burn Association:

The severity of a scald injury depends on the temperature to which the skin is exposed and how long it is exposed. The most common regulatory standard for the maximum temperature of water delivered by residential water heaters to the tap is 120 degrees Fahrenheit/48 degrees Celsius. At this temperature, the skin of adults requires an average of five minutes of exposure for a full thickness burn to occur. When the temperature of a hot liquid is increased to 140o F/60o C it takes only five seconds or less for a serious burn to occur.

So you can see that I'm pushing the limit on temperatures and there's no need for any fancy equipment for heating a single small towel every day or so.

I do find that the hot towel really helps with my shaves, but if I'm being a slacker, I'll skip it.