Unlike the search operators these are not something you can add to the Google search box but these modifiers should be added to the SERP (Search Engine Result Pages) URL.
+ &tbs=qdr:h - Results from past hour
With this URL modifier Google will display the results from the past hour. To trigger this just add &tbs=qdr:h to the end of the SERP URL. You can also modify the parameter to show different time ranges as shown below
— &tbs=qdr:s - Results from past sec, e.g. star wars — &tbs=qdr:n - Results from past minute, e.g. star wars — &tbs=qdr:h - Results from past hour, e.g.