SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '476c9f89ee9ad8294259f4810fca52269c43cedd964a68e04297612f20c9520f' 
  AND token = 'UrQsydEdj7Enaw1NXFLQ9UgeCFKgD8QLrcUKBI4dXII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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