SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e81ab406828157e06dcdc57f18a430655402e78a890d1441666cb222f600953' 
  AND token = 'ezvATUThlYcgPQnkyzMrpOWSUg3D4vSMPMQUjd6wax4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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