SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7134dfd31659e747015526598e94a1236f4ec6bbf0f1b01f50a68b7e4f7be98c' 
  AND token = 'WLlg7HVYZZqjv4/q/Gkvh2Yc160N7Lwl7q+KjhpC98g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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