最终，像Keshan提到的那样，在用户名列中添加了一个FULLTEXT索引(以前只有一个唯一索引)，这似乎使速度提高了10倍.查询大约需要90到120毫秒.

Ended up adding a FULLTEXT index as Keshan mentioned to the username column (previously had just a unique index) which seems to have speed things up 10 fold. The query takes about 90 to 120 ms.