SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15a4f493796b7238b13d3490f193d90b0a31028592bff78eafe58f0a72e73c26' 
  AND token = 'dfIjEXVi+xanUy8sLZdsxrqjJHQ4yuPBL5Dwj/FGoh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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