Do Thermal Cutoff switches exist for temperatures below 50 C?
Yes, thermal normally-open and normally-closed switches do exist for temperatures below 50 Centigrade. 

For instance, see the catalog of Thermtrol Corporation, which has several options.

Searching for Thermal Switch on eBay yields this result - a Normally Closed thermal cutoff switch for 45 Centigrade, rated for 250 V / 10 A.

A little further digging might yield better options or prices.