Catalyzes the liberation of alpha-xylose from the non-reducing terminal glucose of xyloglucan oligosaccharides. Has high hydrolytic activity on the disaccharide isoprimeverose. Follows a retaining mechanism of substrate hydrolysis. Hydrolysis of terminal, non-reducing alpha-D-xylose residues with release of alpha-D-xylose. Optimum pH is 5.5. Optimum temperature is 90 degrees Celsius. Monomer. Belongs to the glycosyl hydrolase 31 family.