SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '366c0e8bea26c893a14dc70587baa070ea00343829d7aa06abc5875d4504a748' 
  AND token = 'Cy6BvGuTeaVxEn2dtI6MigpXY20jv6wXvAWRRqmsmSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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