SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fa7df110cb141729aff7ccfdb8537cd10d1fb782fe6221a1540da4b6443c54e' 
  AND token = '8jBC8NsKJfzgf9DPj6hPanB/VUhJvEExF5QkC/bkJXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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