Absolutely not! I have never heard of an asexual snail and doubt seriously if such a thing exists. Where on earth did that myth come from?
Common ramshorn and commpn pond snails are hermaphroditic - they have both male and female organs and can function as either sex, but it takes two to tango - one functional male and one functional female. They can also store fertilized eggs or sperm for future use, so a previously fertilized snail can produce viable eggs over an extended period, similar to livebearing fish. But these snails have both sexes, not no sex.
MTS are parthenogenic females, and can produce viable offspring without fertilizarion by a male. But they are anatomically female, not asexual.
Apple snails are either males or females, not both simutaneously, but also always one or the other, not asexual.