SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '01a76791dca6a558f19f849a04e0f51f38f532be902ac7cc583d1707adff37b4' 
  AND token = '6APPkMpXz6vaEMM1aGCj+oviYHgpqaZ1YhmQgrRMVTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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