php – how to decode and print json in smart3-ThrowExceptions

I am new with smarty. I have a key value paired json stored in my mysql table and I want to decode and print it with key without a loop. for example.

{
    "A": "100",
    "B": "200",
    "Cart": true
}

found decode method

*.$json|json_decode:1|print_r.*

but how i can echo like in php $json['A'];

{$myjson = $json|json_decode:true}

{$myjson['A']}

{$myjson.A}