SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b302adef6f5faf2ee3cc3abe8a509f7126e10c60e4ea41373d9d6fd3338d7e41' 
  AND token = 'r+KRzd9xBERJlVy1GcIee7hKcIZJFYkYJRO9mxyarQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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