MyISAM I think was the table type that did NOT support FK constraints and was blazing fast. InnoDB had FK constraints.

You would fully normalize, use proper joins etc. But without FK constraints you could end up with orphan data... Not the worst thing in the world, depending on how the joins in your system were structured.

Care and diligence were the order of the day. You had to know your schema and make sure you were doing the RIGHT thing at all points in the stack.