SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e176d109454261a76f917cabfe1455d98b20143090a8edbb75a57046959aae08' 
  AND token = 'RDFJdcBtbBQzSt+w/6fhWKWvVwBUjREsQTZaw0Sueuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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