SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99236a264f66a0d715d0eba11a7e35de124c5cd6f6948ec8d8de73b917b879cd' 
  AND token = 'H6wSvdt98VPyQMQPoKolfLhI2JqgXkyZsnC/TwGe2C0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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