SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e9f45fb0934e6f1656f82990d1ee68c531ec92f1ae0cbefd23d273a43a18728' 
  AND token = 'Dz754+uteiHL1DbUXjTlZYz+swTVGRG8Tg76Jm3i9H0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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