Well, you can try using “EXACTLY LIKE”, that might be a bit better, but may not work as you want it.
Filtering on custom fields and taxonomy terms is an extremely hard task, and unfortunately there is no way of indexing it. For generally large databases with a lot of fields I usually don’t recommend using filters.
For the absolute best possible berformace: Only a search bar configured with the index table engine – and all the custom fields can be indexed as well. Without the filters it can be very fast.