SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86ba1b35bc947ea722574471f289878c9627b8cdbdad9d48344c4dc8e5d6bc37' 
  AND token = 'Z5AjjM+rJ8RfswbPA2pDUDzHNEmHmr5eoE+xms0DFf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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