SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '405495da5bfb2bb60e89a912a17592d80f74ee673e18ab16259039a3a9c23caa' 
  AND token = 'UzHa7hLOk+hVVxWsSt9OcxEahtNed3l09f2bSqt3Zto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}