SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9218c4d92870881a99502cbf171cf6fc93186eac11ce2f372c789e303e320bb3' 
  AND token = '8CsN1xp1hMgqTS79iSncOJOI9+adKDPWANBTaJ0rL4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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