SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b4358492f8fd714a9763418877acaf6ef5d748c939681cdc04929643355730a' 
  AND token = 'uWAh+rswnwkyqt/3jqF68WuKZXb7bKiZJqtYuMbQ+Ms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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