public partial class Form1 : Form {
    public Form1() {
        InitializeComponent();
    }
    private bool prefixSeen;
 
    protected override bool ProcessCmdKey(ref Message msg,Keys keyData) {
        if (prefixSeen) {
            if (keyData == (Keys.Alt | Keys.Control | Keys.P)) {
                MessageBox.Show("Got it!");
            }
            prefixSeen = false;
            return true;
        }
        if (keyData == (Keys.Alt | Keys.Control | Keys.K)) {
            prefixSeen = true;
            return true;
        }
        return base.ProcessCmdKey(ref msg,keyData);
    }
}