Uses all registers A X Y, keeps history, to detect key press & hold. If joystick(s) will be read, to avoid interfere, this method should be used :

https://codebase64.org/doku.php?id=base:both_joysticks_handling_plus_proper_keyboard_scan

lda #$ff sta $dc00 lda $dc00 …

;64tass format

	* = $1000
		
	sei
loop	lda #$80
-	cmp $d012
	bne -
		
	ldx #$00		;key #0
	ldy #$7f
	lda #$40		;Q
	jsr keyscan
	bcc +
		
	inc $d020
		
+	ldx #$01		;key #1
	ldy #$fd
	lda #$02		;W
	jsr keyscan
	bcc +
		
	inc $d021
		
+	jmp loop		

keyscan	clc
	sty $dc00
	and $dc01
	beq +			;key pressed A=0, update buffer, C=0
	cmp keys,x
	bne +			;key not held down, A!=0, C=1
	clc			;no keypress, return with C=0
	rts
		
+	sta keys,x
	rts
		
keys	.byte $40,$02	        ;initial values should be A values