SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '577f76ce88367b026c99fe2ddc7d1a0377700df78e860f9e4cff80312c48625d' 
  AND token = 'SlAYJzJw6h9xwXI58DS5lC+mgXwyK3oyCUDoUTOODsw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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