SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '836e6f9650cb9d2139b84dbe3d5519672b71f769ad8b2d41fb53404ab650bb30' 
  AND token = 'oPTDF/yznnhzZe6Q2JeH/slmB8OdV9V2eMqUqWh/aJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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