SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '505fa1697e4309281e29621b69a95e8bc1d0cf222bb523234056de1542e0e685' 
  AND token = 'ZjY1VeGbDkeNpkcZ2Ac2yCYIbZJzajUC830/gxrwRQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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