Tell the short version first
Did the door close behind you, did a key disappear, or did the lock stop responding to a key you still have? These are different situations. Say whether anyone has another usable copy and whether there is another entrance you are already authorized to use. There is no need to suggest an opening method yourself.
If the key has gone missing, getting inside may be only part of the request. Once access is resolved, you can discuss whether the existing lock should use a different key. That decision depends on the hardware and your authority over the property, rather than on the urgency of the initial lockout.
Make the meeting point specific
Give the complete street address and any apartment or suite number. Near Lancaster's Town Square, a shop name or Dallas Avenue alone can leave the actual doorway unclear. Explain which entrance is involved and where an authorized person will meet. For a parked car, describe its location as well as the vehicle.
If a child, person or animal is in immediate danger, contact emergency services first. Otherwise, wait somewhere safe and reachable by phone. A vehicle lockout enquiry also needs the make, model and year, with suitability confirmed before any particular car-key service is promised.
Ask before the work begins
Ask what availability can be confirmed for your address, how the charge will be explained and what evidence of authorization is required. Tell the person handling the enquiry if you rent or if the entrance is shared. An owner or building manager may need to take part in the decision.
A changed assessment should lead to another explanation before extra work is approved. The pricing questions page gives you a short checklist for that conversation. You can be clear about your situation even when you cannot yet know which repair or opening approach will be suitable.