SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c47fbb7fa971a7aec89614676dc696b9bad032586efb3fde78cbb52bab67ce8' 
  AND token = 'p2JaTSTQ39jGsCB4pcBuUSkzyVp4Nvx4KYELGPoKDsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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