SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16e8756b5fdf7524fa9a33977cea7ba21bcfb5096d7cf42c3188e9be230477a5' 
  AND token = '6oEVwZILAXQbJQhyGSeUSMB4WdfqKAQmNeLPWjkKcBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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