SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e497938e98cc76263f7180fdf86386e394399d1a517fcb773a43eec972e031d0' 
  AND token = 'UpeYZcdAbShCPeimZ5FJ84rb1mqes7WLETzR1iJl2qY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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