SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb9cef7ff96663ab109d21992ffc16bd7519f0ef3998e06231789c7087ba1602' 
  AND token = 'GW4iTvqnyVdtQGi8OuRnDfDPF80h2aj+ZWW2IAGS6PI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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