Rate Per Second = RPS
Suggestions to consider for your my.cnf [mysqld] section
key_buffer_size=4G # from ~ 64G since only 2% has been used
key_cache_age_threshold=7200 # from 300 seconds before age out
key_cache_block_size=16384 # from 1024 to minimize number of blocks to manage
key_cache_division_limit=50 # from 100 for Hot/Warm cache
these changes will reduce key_reads well below current 29 reads per second. For additional suggestions view my profile, Network profile for contact info and free downloadable Utility Scripts to assist with performance tuning. Tables are being scanned 7 times per second, indexes may provide relief. EXPLAIN SELECT (query) will help identify missing indexes.