SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '038636d971c42fa95542ee741c061fa2163115001e95e66c8e57a3403d3d943c' 
  AND token = 'EVjWOqEkhJk4OdpxRjLYVmbB7OgQ4aV/zrAlY6by+Zg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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