I've been training (US-based) for about 5-6 years. I was lucky to have the option of finding gyms that weren't sexist in the ways you described, but in visiting other gyms or trying other gyms to potentially join I have experienced a lot of sexism.
In the US, I'm considered a fairly experienced amateur fighter with 21 fights, but when I visit other gyms I almost invariably get paired with the only other woman in the gym, regardless of size or skill level. This drives me nuts, because I'd much rather have a partner with comparable skill - whether that person be male or female! It also poses a problem as sometimes there are men more appropriately sized to work with me, when I'll get paired with a much larger woman. Combine that with a skill discrepancy, and it makes me feel like I'm only good enough "for a girl" and not to train with the majority of the fighters.
In sparring, I get a lot of guys trying to go light on me but they go so light that they're basically shadow boxing or going super slow. If I pick up the intensity, sometimes they get mad and try to hurt me. Neither is beneficial. I also get a lot of those guys that just shell-up and say "hit me, hit me!" and (maybe this is just me) I find this super condescending because if I wanted to just hit something that doesn't move I'd hit a bag.
In some cases, I've asked coaches (that I'm more familiar with) "hey, you paired me with her, but I think this other person would be a better match based on skill and/or size." In my own gym, I try to take my turn teaching newer people how to hit and hold pads - we all have to learn. But when I'm paying to drop in at another gym, I am paying to work, not teach their new students to hold pads.
The biggest thing I've learned is just to advocate for myself. It's really hard, and the response isn't always what we want but I find that 95% of the time people don't realize they're behaving in a sexist way and didn't realize how you interpreted what they did. Sometimes I've been given really thoughtful reasons why I was partnered up the way I was, too - trying to inspire a student who's expressed interest in fighting by letting them work with a fighter who "looks" like them.
As for the "boys club" part of it, sometimes I find this. I always ask myself if I really want to be in that club. If yes, I assert myself. If I have valuable knowledge, I put it forward. Sometimes though, I can see that this is a group I don't care to be part of and I have no problem just walking away. I'm happy to share my thoughts if they ask, but unconcerned if they don't and that they don't consider me one of them. Many gyms have cliques and sometimes those cliques are all-encompassing. I'm not trying to join a Muay Thai cult - just train and fight and make some friends.
I hope this helps!