SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81437c2792ad350160d481a777850f497b92a952064fb951eda2e0f6ea45deae' 
  AND token = 'cZrI+WIj6A2rtXnEYAeUnU8iEFCtLLRVqUNQ2XwgQsA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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