SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae2c2b41eea45b39bfb982c0249f43a863592b0cf7363591a774bd90fe3f0c29' 
  AND token = 'E7iv1hGoJUtngpZQ7dppDdufRoD3MIDG5/JfMQcKkDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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