>>699
card={"ID":"python123","PASS":"python","an":"1234"}
card_input='ID'

counter = 0
while True:
counter += 1
if counter == 10:
break
if card_input in card:
print(card[card_input])
break
else:
print("違います")

結果はPython123
keyじゃなくてvalueがあるのか知りたいなら

card={"ID":"python123","PASS":"python","an":"1234"}
card_input='python'

counter = 0
while True:
counter += 1
if counter == 10:
break
if card_input in card.values():
print(f'{card_input}はある')
break
else:
print("違います")