SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f945a331f83fa6c86c8488d21c036dec552051db849ed7338ad9ba4a627ac7d' 
  AND token = 'FQwFkIvJFL0yQV7XsrprByjkUierYa9yZbHZCYx+QrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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