SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aacad39f4fdbb9bf5d3b91efb5e08d2962de573284cbe977fee91b6873f93d3d' 
  AND token = 'RpgYUEVMYg1PFZYCaFOlOM+mf+h9tY/4QMh+oXEjmZw=' 
  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"
    }
  }
}