SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83de0192cc53e882809b5a8bad1ebe4b735ea7f47e0e6608824ff05960f2ae4c' 
  AND token = 'RRml9GY/95BFscIYsfvGkBgDQUeO8cYuWH3NHy1qWfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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