The details shared here apply to the most recent version of Turbo. To keep your theme up to date, check out this helpful document.
Enabling the checkout button's lock icon
Turbo gives you the option to enable a lock icon for the checkout button which will appear on both the mini cart and the cart page. This subtle option is a great way to build trust and assure customers that your store is secure thanks to Shopify’s built-in SSL feature.
While this may seem like a small change, research and best practices indicate that the simple addition of this icon can help increase conversion rate, by reassuring shoppers that their payment and personal information is secure.
To enable the icon, head into Customize > Theme Settings > Cart > 'Show lock icon on checkout button':