Currently as per Box's community article, all searches implicitly include trailing wildcards:

"Trailing wildcards are implicitly included in search results because of the way text is indexed. Searching for Bo results in items with the words Box or Boat or Boxer. It is the equivalent of searching for Bo* or Bo% in traditional search engines. Traditional wildcard notation is not supported by Box, such as %ox% "

However, this leads to search results that are both 1) too wide and 2) not intuitive based on search norms

i.e., one would think that searching (with quotes) for " Box " would only get results with Box as a standalone word. However, it currently also brings up content with box as part of the word, e.g. a file named helloboxers.