CE560XL flight crew reported landing gear downlock malfunction. Flight crew landed safely.

Narrative

We departed ZZZ1 on Day 0 en route into ZZZ. I was performing the before landing checklist and on final for Runway XX. I called Gear in Transit and then noticed only two green indications on the landing gear. I also observed an indicated red and illuminated unlocked indication. I called for the Go around. PIC was flying the aircraft and initiated the go around. I notified ATC and went to the QRH and performed the QRH and procedures of the Abnormal Checklist. We completed the Abnormal checklist. We were unable to extend the gear manually and confirm 3 green lights and continued to indicate an unlocked indication and only two green indications. I talked with the PIC and requested priority handling. I communicated with the PIC; and we made the decision to request a low pass over the airport. I communicated with Tower to verify if the landing gear was down visually. Tower said that the landing gear appeared to be down. PIC landed the aircraft safely and the unlocking indication went away upon landing. The aircraft taxied into the FBO; and we had emergency vehicles and airport ops follow the aircraft as a precaution.