The short answer is that, in a perfectly insulating container, yes, there might be some heat given off by radioactive decay. Radioactivity and radioactive decay give off "potential energy" that was stored in nuclear bonds. Chemically, two atoms can combine together due to electric forces and quantum effects to form a compound (sometimes releasing energy because the bond is more stable than the free atoms, sometimes storing energy in the bond). The nuclear energy is basically the same thing, but it's caused by the 'bonding' of protons and neutrons into heavier nuclei with something call the "strong nuclear force." This force overcomes to repulsion from the electric force on two positive protons at short distances and glues them together and it's still not fully understood by physicists today. Light atomic nuclei, like most of the ones in honey, give off energy when they bond and are therefore very stable. On the other hand, very heavy atomic nuclei - like very 'complex', unstable molecules - take excess energy to create. Plutonium and Uranium are two of the most famous examples, and even 'light' atomic nuclei like Iron are usually only made in very high energy events like supernovas (exploding stars). Sometimes, you also get unstable lighter elements when there are extra neutrons inside the nucleus. These are what are called different isotopes, and a 'heavy' isotope of carbon might decay in honey.
So , indeed technically there is some radioactive decay in honey. However, there are caveats, of course. Honey has a very long shelf life, but I suspect that the decay of the honey's chemical bonds would create more heat than the decay of its atoms. I am not a chemist, though, so I don't know much about the stability of these compounds. Additionally, as others have said, in any sort of 'realistic' environment or experiment, the amount of radioactive decay would be so low that they heat would dissipate and the change would be almost unnoticeable. Maybe on some far away planet there is "uranium honey" or "Radium honey" that does have more radioactive decay.