The search SQL and/or Hibernate HBM is creating two indexes on lockkey, only one of which is UNIQUE. There should be only one unique index created.

CREATE TABLE `searchwriterlock` (
`id` varchar(64) NOT NULL,
`lockkey` varchar(64) NOT NULL,
`nodename` varchar(64) DEFAULT NULL,
`expires` datetime NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `lockkey` (`lockkey`),
KEY `isearchwriterlock_lk` (`lockkey`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8