SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f99fb83ca0200ea3dcc4ef0d250def17a8a1bff07217d73005b8250600f38385' 
  AND token = 'o1YvXEAQJuhr19Skfv5ejbdaI4zen3pdMguj3ojxtTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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