Many thanks to arias1292 who shared her selfie with Keanu on webstagram.
Many thanks to _chantel_marie_ who shared her photo with Keanu on webstagram. She ran into him at work. Looks like a cafe or coffee shop. The photo was definitely taken at the grocery store Vons . She also posted another photo in the same area with Diego Luna and the comment with that photo has Vons in the tag.
Update: Many thanks to brendamage2 for sharing her photo with Keanu on webstagram.