SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f01a3e249b52adffd98ae4b42f433bd174e8eaa60d52bea027ed123d5cd54a8' 
  AND token = '98YW4AmKiUROcDAsj8jGJqdFaVjWhZvR3fqtnVmaVMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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