SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e8d3d86da9e8ded80c340bf9a983894a99d38ff5edc4b4201943516afeadd6a' 
  AND token = 'TgVm1MYqx4SMXZEgj3QmLXjcDLDuJBTU7/kWQ4I7S9E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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