SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f37d42e233241cd89954d83965d4dbdac8fdebdee226006293959dc62956732f' 
  AND token = 'ue96HzsGmqc2a5viZeZBPmqiUuqdMOUNCNGvZl/Jxr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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