I'm not sure if any dating sites have that option but I would just recommend being very clear in your profile and communications about your sexuality.

Best of luck to you!

I would think most dating websites, if you are clear about your preferences and labels..even this one. There are asexual dating websites, but I never saw anything so slow..some threads run over a year with people posting replies every four months or so. For most, apparently some sex drive is useful for dating motivation..otherwise, why bother?

As long as you are clear and use that keyword, it should key other in on it.