SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '671a9eedf3eec1a7e301f817bce9bb2e9027cc084a8a92110c22acc2607a969c' 
  AND token = 'VdIvUUSkcL/yJH+uRxh1WLlVkE8SkDevskaQpHeKwcA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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