Problem:

_(…)
KEY `value` (`value`(250)) _
) ENGINE=MyISAM;

Error Code: 1071. Specified key was too long; max key length is 1000 bytes

Solution:

KEY `value` (`value`(250))
-- ) ENGINE=MyISAM;
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

alternatively:

set global innodb_large_prefix = ON;