SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c824dd08674a99637c68fbb0e32726d83aaf87612a48215b619905d9f389953' 
  AND token = '2+mEfLqDxYcm4QjqaRVbRf8xDTIfYlXaT2LhSUc1hy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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