There are lots of payment processors who will deal with explicit content. They tend to be fairly expensive though - partially justified since apparently chargebacks are outlandishly common. For example, CCBill will process essentially anything that isn’t illegal, albeit with 6% fees for “risky” industries and 10-15% fees for “adult” industries.
https://ccbill.com/pricing
(As an aside, one sort of neat thing about CCBill is apparently they’ll never kill your account without warning, unlike PayPal & co)