SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96a0281475a1640dc8c35f8300d2e8e853341dbe0820cfc7841d99d09e6920ec' 
  AND token = '/YoeFfQGGmcQTl+OMABEkM/bj8+zGwDqhY+ib5Wz8xE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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