Inside TYPO3
3.3.4. Browsing $TYPO3_CONF_VARS values
In the module Tools>Configuration (extension key: lowlevel), you can also browse the $TYPO3_CONF_VARS array and its values:

Notice: This module is merely a browser letting you comfortably investigate the values configured - you can not change the values (although it might seem an obvious thing to add). There are currently no plans about adding that capability.