SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a6a51cc5c20287fdcc73774d26f30f3be4f8bca8fe18bd19364f275bb02d078' 
  AND token = 'plLI50SyzwyEqJyBbcZemovN/xWFgYFJqK8OyDDZXms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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