60 to 70% humidity is ok. Even if it drops below 60% won’t harm the snake. When shedding the humidity should be no less than 70%. You said the warm side is 80 and then you said well it’s like 90. Well, if he has a warm side of 90 would be fine. The warm side should be no less than 86-88. And be prepared to upgrade your enclosure to a bigger one once the snake gets bigger