Jquery Find method format

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jQuery

DynamicMethod

if (this_call!=null && has_value(this_call.data().process_step))
$container.find('.col1:[key="'+this_call.data().process_step+'"]').click();
else{
$container.find('.col1:[key]:first').click();//Error
}

i got error "Syntax error,unrecognized expression" on below link
$container.find('.col1:[key]:first').click();

every time when button clicked at that time button number(0,1,2,3) given by below line.

this_call.data().process_step

".col1:" define in CSS

.col1{
box-sizing: content-box;
color: white;
width: 75px;
height: 75px;
line-height: 75px;
text-align: center;
-webkit-border-radius: 10px;
background-image: -webkit-radial-gradient(20px 20px, circle cover, rgb(201, 201, 201), rgb(165, 165, 165));
-webkit-box-shadow: 4px 4px 20px 4px rgb(196, 196, 196);
border-bottom: 5px solid rgb(172, 172, 172);

font-size: 16px;
font-weight: bold;
text-shadow: rgba(0, 0, 0, 0.4) 0px -1px 0;
}
.col1.selected
{
background-image: -webkit-radial-gradient(20px 20px, circle cover, rgb(34, 214, 0), rgb(19, 156, 0));
-webkit-box-shadow: 4px 4px 20px 4px rgb(185, 185, 185);
border-bottom: 5px solid rgb(25, 172, 84);

}
.col2{
box-sizing: content-box;
-webkit-box-flex:1;
padding-left: 20px;
}

can any tell me how to define dynamic value in find jquery method