SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02736c5b06d6cf8535235e9ce72eb1431fc44f17a52731491b3063aade5f0f12' 
  AND token = 'vfFPMOC69KCZxKCqWqGj//xY+cw9yRGh/z7kq6k+Ibg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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