SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d68c4240c96dae08272351f0e81e4a5142c013798c5bb921827ced512cde932' 
  AND token = 'PuCorO8WXpkiR3uiDFvwM/Kjy7d4jQR1opdLG0JGWpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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