SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28287a63092a464bd4a2d33e30b361d4610bf71f55a5faa8e3d87fb60dcfda38' 
  AND token = 'cVxWbQvn9z0zEs+EDY37zIOTBph8DZvPwtnnOYqnJPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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