SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54d5c888af83b5d95a509db6815ac965129cda6d2a339683f30297f785d71322' 
  AND token = 'KJt9K/ddEvH6KzOkMin01XxzA+MgCRaJRywFYGaPHHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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