SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4716df9ce1a5c251a1a3e978fd74336ee7d9bd68c1ffa70b5a637da6874e0839' 
  AND token = 'O5mcnSJ9zFVNRQ2ee+DJzn3UU1blGqTt/WEwjUsAvYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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