SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '83b8a976eae7716363c57fb680656a0923df41f544d37a05767bbea226c809e4' 
  AND token = 'tOi9sIggLoK19hxDSMkJC/ug3sKJ3z4By/lqEi5UCl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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