SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6e85af05e3279c62066f68cf25bb0a5e8c10b69a7daec0c0bd820c1e5831cc7' 
  AND token = 'QWTE8lqM3JMTrUWBiVLuLTxqe0qhC2J/UTuTADTUxtU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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