SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '306592407b639fef8c0de82b9bab7d46d8fc9c78fd6c2f9db6f21943f6b8c34a' 
  AND token = 'Oq1YcYRF9j3GsdEasLjOUgBAI5kTmlgzHcQDoV6/pTI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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