SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4a1684f2d8b0f806780f6a7a95c435aff1e4f216761ad91d43fc018fc675e28' 
  AND token = 'gmsBijq/uddUWSMu4jHZPpTvzaNsPCp60DS+3QqJll4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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