If you need credit card icons and other payment icons for your online store like Mastercard, Visa, American Express, Paypal, etc, you can download them for free from here:

free payment method icons

Free payment method icons

Includes: Visa, Mastercard, Maestro, Cirrus, PayPal, Western Union, Visa Electron, Amazon, WorldPay, Diners Club International, Skrill, Sage, Discover, Skrill moneybookers, JCB, eBay, eway, Direct Debit, American Express, Shopify, and more, in both light and dark versions.