MCO is dangerous because Orlando makes every plan sound fun. The airport is not beside the theme parks, and security can be busy with families and vacation traffic.
What to do with bags
Do not build a plan around lockers unless you have confirmed an active service for your terminal and timing. Airline early bag check may be the better question.
Leaving the airport
Theme parks need a very long layover and a willingness to spend real money for a short visit. For most travelers, a hotel pool day, nearby restaurant, or Disney Springs-style plan is the upper limit.
Getting back through security
Return early during school breaks, holidays, and cruise-heavy travel days. MCO lines can expand quickly.