SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df451dbd64ecc120b3675e92533a0919545bfb39007ddb11421d60ea8985ee80' 
  AND token = '38wUjmKOxTwEXjr45pAmTCKsMoUCANZqMM7ptBfx9oE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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