I tell my customers to NEVER microwave honey. The heat is too high and will change the flavor, destroy the healthful benefits of the enzymes in the pollen, and dehydrate it to the point it can't be liquefied anymore.
I recommend running water in the sink to a temp that is as hot as you can while still being able keep your hand in it, then stopping up the sink and filling it to the level of the honey in the container. Leave it in the water bath until the water is cold or if you are in a hurry, watch it until it is liquid again.
I don't even like the recommendation on the labels you can buy from bee suppliers that say to heat water on the stove, take it off the heat, and then place the container in there, as it could be too hot.