SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45175598feab53157f0a9911857f89c4e9d58694bbcfaf896ceef9f6dded0251' 
  AND token = 'B81YYXkkNGzKQDlJCiWWMhWwSvZijUXGz5gQpzpSvKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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