SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c15b19892a1f1e8bb5b5bfe048b1c2e76bd86ba7fc77c5013f3fb4d834cbc9f' 
  AND token = 'q/+5mEaxSLjDVfZ5EE9JItMNa3roKy3P+vahwIoHdPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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