SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae417fd38788f35e661953248ab9ce8d500b6454d1ac2b4a5c73d9621da47817' 
  AND token = 'UOA3h+72vXjBw6Vh2C4oCftPOnTn+v0mEtgTBPg/QJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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