SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8b61c520f2268398176770434257dbcd0d9d23e34cbbd9e145cbb69041f069e' 
  AND token = '6Y5vt266HJlM/3XGKJpZJ1VYBTwEwveLaDLcseoxk5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}