I know roffman is not wrong. But, it is just mopeds man. I have had a few kits of mine soft seize. Usually going downhill and probably not advanced enough timing. However I have put hundreds of miles on soft seized kits with no additional issues. I will remove the head and inspect the cylinder. If it feels smooth still and not scratched or pitted in any way then you are good to run it still. The shape of your cyl matches the shape of your piston and rings.
You can obviously still end up with some blow thru but it wont be much. Obviously address your possible causes such as air leaks or timing, but running it can be just fine.
My concern now would be that you snapped a ring. The new ring will not match the new shape of the cyl as well as the ring that was in during the seize. You can lightly smooth out your cyl if it feels scratched up, but any amount of material you remove from the cyl walls will be gaps for gas to blow thru.
Again it's just mopeds. Be safe but have fun. Fix thing when they break