SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2558c1680cfac95578937187931eb81857d7caaa35f0b953896167634a0ee648' 
  AND token = 'SUpnEQV76j79wHQhqVkRZp+S+mnygWwvOi9OZWhoTMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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