HPCC-11551 Update mySQL key file to match updated query

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #6151 from ghalliday/issue11551

HPCC-11551 Update mySQL key file to match updated query

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>