SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40f15c6e7313106df24bdade04663985278eacc537e43d5a62cf5e1eec6e2869' 
  AND token = 'KbIDPfjhEjqbS3qRS4DdClhhQhhJqXWcBhLiG0utoeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}