SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29f934d455c0254c93138446dbea4d274329859299f8ec393e9a08695cbd0c98' 
  AND token = 'h8sVC+ZWzBxbfUnhPv/wlbjUlPTmafv2y9gzUJrHFd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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