SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8970a6e00638a888076b528e8365eb17716f3e75a297de23584f6e8d60125f08' 
  AND token = '0qCd9wMkiQh2hTXkLwvMzm11GqizoW2sHHs2wqSoyzs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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