SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '689b80ab3f1dc297ad086c3502096ee70d766fde049eba5107f6226108e2e364' 
  AND token = 'laS02kP+PC+gsSKfT22gUOsumoOytcMbrgnmmaqRXpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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