SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7420be0bb660504dd009c401f2add54bf72ccc3a4860115af07129d12bc46a1f' 
  AND token = 'z0XDHu/Ecs8P39cBKmJKbGcUXVUgFPCtPKBUUps7sIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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