The PageTime(StartPage, EndPage) function will return the number of seconds the respondent spent between those two points. You could do a simple logic statement like PageTime(1,10)< 50 as skip logic on any question. If the statement evaluates to true (their page time was less than 50 seconds) then the skip would send them to wherever you wanted them to go.
You can have as many separate terminate points as you want in a survey, just separate them by page breaks.
If you are in an older version of the software, you'll need to double check if the PageTime function exists. Open up the Help documentation and in the tree view of subjects, navigate to General Survey Help -> Composing Surveys -> Sawtooth Script (or SSI Script in old versions) -> Functions -> System Functions. The path might be a little different if you are on a very old version, but it should be something similar to that.