SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8a7209b0e2d5f62520b4fa09a66f2b6e20da5dea0d55894830920fbf216abf0' 
  AND token = 'tX8r+obYBOdpPH0dxmJHesqm7HZHVF+gTNrVtqsllcQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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