php if statement in array

I have code like this

$insert=$db->insert("INSERT INTO `wp_postmeta` (`post_id` ,`meta_key`, 
`meta_value`)VALUES(:id,:meta_key,:meta_value) " ,array(
                'id'=>$id,
                'meta_key'=>$meta_key,
                'meta_value'=>$meta_value,));

I want to have if statement for meta value like this if $meta_key == 3 then meta_value==landan