SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18d9f1a473bb2c78f85dc892c78b929de3f8f6d491c572cf7b41d94657c86d42' 
  AND token = 'sMXBm/Ni0RAGJlGtcAzSIh9CyqvQJ3Z2AZomQhUX3M0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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