SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c29243529644d8eac68821089aba39cda57394cd007aff3a19b4673211c254d' 
  AND token = 'J8qwo8mWuYsM+tVd/zpktVIzjiRH9Ob4sAy0nTmNoAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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