SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dc3cc67b6b4bcaa1fd34437327d09d9608974e206e0a2f9a5e53835371b6921' 
  AND token = 'wWVVObaUPJW+/CvljHG7HpPu5OaSRxdyEDTjMrAuuiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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