SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1c9c59c39c940a14d759fc86cfd34f6ae6270d56d561d37333fb92230fb0353' 
  AND token = 'x6WYKJqUn81Qzt4olLBYaP7bjhkITlklmRUjGkYtmP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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