SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e673d121b32e27ac754c93b0bf77ec211b3268a68e81b539cb3a6d7e8c827d24' 
  AND token = 'PzWpnvZuuVcMPtTZB3wfE5f59wKV3PITP+NYf2zViys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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