SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '398695d6dbbafe649c2ef9c55d3dbc985b51ecc71583a466687496e6a0a36094' 
  AND token = 'uwiLdCPJ4O4+SEdwrNfw95uzB7oKPQVi+xs8uk51Ick=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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