SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a23ca84b776fe535d38f614e09f4a55821c65ba655ccced3df015431edc83ff6' 
  AND token = 'aEdbhm37RNFrypautmsZrrh5iaddUAeLkfA8rHE5QVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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