SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aac975e9eae0d50f5ba4f4c35cbfc28f337509b715c1d9afb778146d8125de25' 
  AND token = 'wTyHvMxF6UiMqMYXnEwUSRjRtQEnt2rVc2P00Jgx42I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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