SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76dc4c6f3d6904722c7582e27354e7727530651d029af548187c5ad8304f7e37' 
  AND token = 'CkG3u6lRE2uZLDPkchnhCwhm0M0kw3DcJBl1WmJIbrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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