SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbf55aa617f3e00a1a02e4529017153ffdda018057d41a250535a21e702ef4d3' 
  AND token = '8PnNMjP6SWz6MLBqap170gn57bSKXYA2+prMehkkCbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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