SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45934afd0d12a964307761419a3d66f981cda06857c63ab3c9c9f97b84390463' 
  AND token = 'beI6lF3T+ypTvll+eIwjZwzP+MkLQKOHB5fDvJD6DqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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