MDEV-21329 patch introduces functor to do get btr_page_optimistic_get().
Basically functor basically checks whether the page is in buffer pool and it is the same page, takes hash lock for the respective page id. But in 10.5 alone, InnoDB does check the page id and page state, takes page hash lock again. The earlier optimizations that were implemented in
MDEV-15053 and MDEV-22871 would allow this to be improved further.