SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '571de4429b8f1ff3fc27756e06662a4f157b1df9dff14d0fdd1a018730f05c45' 
  AND token = 'ER/xshV0zID64+YtZxqYQOJIfg3uP2gWm6/C/NOBYY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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