什么是这个SQL注入攻击，我该怎么检查才能看到我不容易受到攻击

I am escaping through PDO all my inputs.
From time to time I see in my logs the following attack:

1 AND 1=2 UNION SELECT 0x6461726b31636f6465,0x6461726b32636f6465,0x6461726b33636f6465,0x6461726b34636f6465,0x6461726b35636f6465,0x6461726b36636f6465,0x6461726b37636f6465,0x6461726b38636f6465,0x6461726b39636f6465,0x6461726b3130636f6465,0x6461726b3131636f6465

What does it look for?