SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3de6583840e746f9de121eca04e6a479b1c94ef620964d972d65f3a43b8bc5b4' 
  AND token = 'xXap5poTj3TSyd8vXw/9xoQbVTCbMOwO/RPqqqgxhT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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