SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76ca0954c6d53b62cdb3f259c12eab42657fadb1c41c98734bc0af1172258791' 
  AND token = 'Izev/KWi/Um96xfo2yHkJwIUCXGnOxqhtG1ajujxOv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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