SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef7afc51c2530da11b66a1506ca1f912479ba33f5ab4895d346059ad54d92b39' 
  AND token = 'asdYhxJstd0bWTir6PAmfc/rmaMVNtOikA5KdSuogT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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