I'm using version 4.0.3 of MAMP along with phpmyadmin. The top of /Applications/MAMP/bin/phpMyAdmin/libraries/config.default.php reads:
DO NOT EDIT THIS FILE, EDIT config.inc.php INSTEAD !!!
Changing the following line in /Applications/MAMP/bin/phpMyAdmin/config.inc.php and restarting MAMP worked for me.
$cfg['ExecTimeLimit'] = 0;