SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43602cb2367a47b9019b643c7e11d01f881420224a5435b12cb324d1ec04e8a8' 
  AND token = '3AB0uzMhiDI+HmKU+fkCQhODWUSGPXLV6kJZw+xOc40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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