[Konstantinos]

pawn Код:

if(IsPlayerInDynamicCP(playerid,Checkpoint[5]))
{
    // player is in checkpoint
}
else
{
    // player is not in checkpoint
}

or if you don't want to check if they are in.

pawn Код:

if(!IsPlayerInDynamicCP(playerid,Checkpoint[5]))
{
    // player is not in checkpoint
}