SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17cd4a382f30e2c24f581d97265068fc51518d02c8322d87c4f020d324bad725' 
  AND token = '14v89Mtkp1RbKg6DoBvIN4/gkb83E2FWRDFCWMWClw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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