SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df5e0800a45f5ab7e863fe329fdc907ed3ae7a002084d2dce2d082ad00dd58ef' 
  AND token = 'n6qspQeOBZxCfiHYYMbIC7E6F6mw1wlWVnZ/fWXydbE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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