SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af5667cc57ad9e2f9cbb559869dc1ea1083e8462c3b2be72aba91a195eb15641' 
  AND token = '5HOgl9JRjFQA2wk43k9ELWlYWDr+zS2UQnSqkaePbtI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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