SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '65ffbc519302603632065ac4f5b581190c5fb28199b97b7806af3e8dccd1eae0' 
  AND token = 'TbmFHCRIuXnE4cjwNymDjWB/1fdNq4rKbO+tYNXY/vM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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