Slow ranking values in MySQL
Create an EVENT to periodically UPDATE a stats table that stores the "last_ID" to which each of the 70 rankings was last pulled, and the current counts for each.

Each UPDATE on the stats table entries (one per ranking), should join the real table with the entries you are counting, and have the respective criteria, setting stats.count to stats.count+real_tbl.COUNT(*), AND adding WHERE criteria to only consider WHERE id > stats.last_id. You will therefore also be setting stats.last_id to now = MAX(realtbl.id)

Each time the update runs, it will be limited to counting only entries added since the last run, and it will find them by the primary key index (ultra fast).