SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f57aa3e96efefd2869d1a75ccb66b973f52ea29d3f660f56516cbca42e8b8f09' 
  AND token = '94w6SJdSAG4pEBn8DlV6JWEcX/5AdusGm5AKxpcP9Ng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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