SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5442e456118ed73443ed563c1bedab2fc5aedc83d8074107c93967b476d919a6' 
  AND token = 'nOqXRg+FFvRUvgrbiWeZWKz4YNzLoaGfnJFPZF8DwCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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