A not well-known feature of the search field in the Hierarchy panel of Unity3D let you search all GameObjects including a script.
Searching for it is really easy: just insert the full name of the script as shown in the picture below.
Pic. 1 – A scene showing all GameObjects including the ActivateTrigger script
Note: the search keyword must be the same as the script name (not incomplete), even case-insensitive.