SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '198a59d85e6b744bdfcc94ffcbfafbeadd0d06b2794c5d51fc5097e88a5b0ff4' 
  AND token = 'zl9hEYFNAxTUHY7CnGsp/7zhmMZRQsn31v4TdJ8UNAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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