I use this

//Removing the keyID from the player and crate item from player//
                    byte item1 = 0;
                    byte item1Index = 0;
                    byte item2 = 0;
                    byte item2Index = 0;
                    //------------------------------------------------------------//

                    for (byte page = 0; page < 8; page++)
                    {
                        var count = Player.Inventory.getItemCount(page);

                        for (byte index2 = 0; index2 < count; index2++)
                        {
                            if (Player.Inventory.getItem(page, index2).item.id == item.KeyID && key == false)
                            {
                                key = true;
                                item1 = page;
                                item1Index = index2;
                            }
                            if (Player.Inventory.getItem(page, index2).item.id == item.CrateID && crate == false)
                            {
                                crate = true;
                                item2 = page;
                                item2Index = index2;
                            }