SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afbb03daa6341bd31da1cbbaf731664137f18192e311435764c0c9982a407859' 
  AND token = 'A+GWJnc0qVgjjAIUuos1m+VqdTVhKIp5qz7+JltmS6o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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