SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31fc8ba9ee5da08c8fe37cf4368dabe4a6b23174b99868c3cff37bcb8394c2f9' 
  AND token = '76qTUX8NtOXm1gevbdSwvQaiLg161HE+8DQQo5YoXPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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