SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ddf5fc59b713bb8469bbc6c7b23182b4c30370e4633e593a5903a1e3c53d108d' 
  AND token = 'b/fteLs9boxnFnUONDjyrYKgOHlurrVK0ZMBBFmMAtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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