Some queries can be optimized; others can’t. This is due to the structure of the query itself, which in turn is due to the structure of the underlying data. “Sargable” is database-speak for Search ARGument ABLE.1 A query is sargable if it can be optimized, e.g. by creating and using an index. It’s a good idea to write sargable queries.
This is what FAIR2 is all about: making results actionable for query planning and optimization, both for your future self, your collaborators, and for any automated agents you might wish to deploy to facilitate discovery.