SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f686bdd3682f8b15128bc35530f2c84cb8e87d8133ae922788b973a4acbb747' 
  AND token = 'xIIwRO0skbKBJtsCnpU4FZobHrlhboflk4lTHDlqv/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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