SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c8897b1261363289dda846175a1da12f999ece8c5f1b5ad4d052de7b258aad4' 
  AND token = 'JhMqHkUmNOmzmDmPHZzyihqG3phlif5lF/+xTKS9tak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}