SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '691daffb3d42684d3b87ec1c3b84ca112e4537f4371e2132ee03e5c921ee9521' 
  AND token = 'UbMIJls1K1D6Up9f5KhCgWEiwdM+d3JtPMHGcEw76tI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}