SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb7e2f687fdfcd45abcf6c7bfadec9bc988d9d152f24826362184c5ef6aec7b1' 
  AND token = 'NU10umhzlBO3KGJHKMgn53Uw0WdMbdiSnbcBfeOfqu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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