SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a41246b8149042ebee185ed98fdc8a07418888c76b7727446d634531a4ca8ffd' 
  AND token = 'gYUEw1ZUkWSu/RyEtaTYgnkMriggV+3uyJTkeTUBy3E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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