SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf765510029be2e7993e0cf2961cc05767121ac5c8d1fd9ce8a8c0e266a0206c' 
  AND token = '+RqVdx+TY9wGunhGzDz5xK/OpbTaMiaXDBF4p/ztWgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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