Preparing an inner join, two tables, thank you

I am using PDO and PHP and stopping injection, all the prepared queries on the internet have one table. This is one that I did that is right:

stmt = $dbo->prepare('UPDATE products SET ProductName = :ProductName,  ProductDescription = :ProductDescription , ProductCost = :ProductCost , ProductQuantity =  :ProductQuantity  WHERE ProductID = 3');
$stmt->execute(('ProductName' => $var1, 'ProductDescription' => $var2, 'ProductCost' => $var3,   'ProductQuantity' => $var4));

Code (markup):

When there are two tables with an INNER JOIN I don’t know how to do it:

$q1 = "SELECT * FROM products INNER JOIN keywords on keywords.keywordID = products.KeywordID  and keywords.KeyWord1  = "$keyword"  ";

Code (markup):

Thank you,