Interesting. I do see a difference in the last line in the EXPLAINs. If imsi_ne is a big table, that would explain a big time difference.
However, that does not say why.
Please provide `SHOW CREATE TABLE dn_insi`.
Let me ask about that '\0\0\0\0hI'. Is this supposed to be some binary code? And you are stuffing it into a CHAR(9)? WHY??? BINARY(9) is designed for such.
I suspect the problem has to do with '\0\0\0\0hI' being only 8 characters. That leads to the question of what kind of padding will happen. I _think_ CHAR will be padded with spaces on either system, and work just fine. Note that BINARY will pad with \0, which is distinctly smaller than space.
If you can isolate a reasonably small test case that shows the different EXPLAINs, please post a bug report at
http://bugs.mysql.com . They love to see cases where the new version degrades in performance.