SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50fa6606ae531e73e5073ba907cf34828f339278da0fd313ff02c432d76f85a8' 
  AND token = 'qgiyq9X3G8sYUvJcSfKLFAsOyT2WKEUA5A/ubL/o3Wc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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