MEMORY DELETE query takes more than 60 seconds of time with 100% CPU load

[URL]http://rghost.ru/57449917[/URL]

Try to execute query

DELETE FROM `db_test_table_copy` WHERE `bid`=2 AND `regtime`!=1407760802;

on this 9.8 Mb memory table. On my server it takes 1 minute and 35 seconds with 100% CPU loading all this time
Server version: 5.6.19