SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7c1ea2a38c8036c7c1e8848456bf9b0f1ed7aa84fafff887012bf21d020ef55' 
  AND token = 'N7DOTqBnyGpKq4lcRo2Y7WZ+pFZM0rFwS3OMoawJFN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}