Originally posted in mysql bugs, but they don't do anything for 2 years
http://bugs.mysql.com/bug.php?id=69219

All late releases affected with speed degradation for this kind of query

Results for 5.6.10-linux-glibc2.5-x86_64:

select now();
now()
2013-05-13 23:25:23
create temporary table norepl_t1 engine=myisam select amount, price, money, id_product from scj_tt_ships;
select now();
now()
2013-05-13 23:25:39

And for 5.5.31-linux2.6-x86_64:

select now();
now()
2013-05-13 23:27:33
create temporary table norepl_t1 engine=myisam select amount, price, money, id_product from scj_tt_ships;
select now();
now()
2013-05-13 23:27:34