There is no luggage storage at the airport and at Cairo train station.
You can find luggage storage at museums, residencies and hotels within Cairo.
Museums that offer luggage storage
Museum of Islamic art
The Grand Egyptian museum- find their contacts here
Memphis museum
Egyptian antiquities museum- they don't really have lockers, they have a small check in office by the gate where they can hold your luggage for a few hours.
All museums are generally open from 9.am to 5 p.m everyday.
Luggage storage at hotels
Most hotels work with vertoe to offer luggage storage services.
Book online on vertoe website to secure your spot since space runs out fast during peak seasons.