SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ebf577f010ea511c5900dfbd46c84033546ec483c216a36815fd32e58594ab55' 
  AND token = '6t6eIGeYc7VAc1QsRyA2nv8kUH6kadHuVISQgKQbNcs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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