SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2039fefdd7e6bb3abe2c647c571a8b76f8d353e926463257d211cd4fd6cfd379' 
  AND token = 'h6xPoyQ9cBGh8xfWMmQRNZtSGhJyAxoXUvvC0UHfqWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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