SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8269edd526a3c6b21b446c29fb9e597324c553771fff54dedd4fd5d1c27375c9' 
  AND token = 'm4r/LQtK1mBDzeTWqdlR3XFN9MgeNvi2nPGvVQjJjC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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