Better understand table indexing best practices
Don't randomly add indexes.  Look at your queries to decide which indexes are needed.  See my cookbook.

InnoDB really needs a PRIMARY KEY.  Keep in mind that a PK is, an index, is UNIQUE, and is clustered.  So don't add any index(es) that start with the same column(s).

WHERE a=2 AND b=4 begs for a "composite" index:  INDEX(a,b) or INDEX(b,a).  Those are different than two separate indexes: INDEX(a), INDEX(b).

Don't use BIGINT unless you really expect to have huge numbers.

DESC is ignored on an INDEX declaration.  However, that does not stop the optimizer from running through an index in reverse order to have the effect of 'descending'.

FULLTEXT is useful only if you use MATCH(...) AGAINST(...).

"Too many" indexes slows down inserts some, and slows down UPDATEs that change indexed columns.

Don't index "flags"; such indexes will 'never' be used.