SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f4ad09a6be22bc7a1cce2a1fae2235148d2d24e899bdd76c557b98584f76330' 
  AND token = 't/DuZrPoU+RAZGUqpaHTLgj3zo0nQ1shposSg7M4IIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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