MySQL Boolean Query Expert

I have a MySQL database that needs a set of well-structured, performant SELECT statements built with precise Boolean logic. The goal is to retrieve complex, multi-condition result sets in a single call rather than piecing data together in application code. You will be working only on read operations—no inserts or updates—so efficiency and clarity of each query are critical.

The tables are already indexed, but I welcome recommendations if you spot obvious improvements that would speed up AND / OR combinations, NOT clauses, nested conditions, or full-text searches. Once the queries are finished, I need a short explanation of the logic behind each one so future maintenance is straightforward.

Deliverables I expect:
• SQL files (or a single file) containing the final SELECT statements
• A brief note for each query that outlines filters, joins, and any performance considerations

If you have a track record of crafting advanced Boolean SELECT queries in MySQL, this should be a quick, focused project.