SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4821c5676aac031aea81b9b513e71fac14e9124074def4ccc943ce51762a3370' 
  AND token = 'n27ZddCJzVbkB03bAA9o3eUvnSmrgfOgE0FUhn84CRU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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