SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6551150b7186a932fef9c8ac83027b01f38816bdcd90f666700dffacd2468075' 
  AND token = 'XFhXJMrYKbOygWVJmlsbFQCOdJbEtIYjDVDjY4dmzzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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