SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9669b18c19681cc530894e9483aac321db82fca35e2846f2b808a6d1c96713c9' 
  AND token = 'UavswFxDAfodPngnHCpTJWvwguO47obzGBwz5eGkvDI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00102

JSON explain

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