SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dff88c406a72404f55042d8526f87f7eb94ec9bca9ca06ef9d5e8df5019b72a6' 
  AND token = 'hHDVx1mqJdeMiM/ZUeMJ1nGCjI3kwOLk/3MZZk3+gG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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