SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b28b65e11d8cf8428592f76b375c8b704b948291e3da3e54587a407a11c5d88' 
  AND token = 'ZKBvyEPPG84JEPnsNwLAT44h9tYuFvBmfXlTuizEfVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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