SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39fa5e9817ab38b95a76687807ee37f1f426d09b8e0350534a03dee7dcfc5c28' 
  AND token = 'm/O6wPEa77+0DY7XeTAmMJxfcoe24PfAbR+gzBwyxDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}