SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c8fd56e61e9cb3e0b4ede9248274712773f23e848661d6e1b45989515e95446' 
  AND token = '04ZkBzgazInjt7JOyznhLeGY8VZfHNxUQOmz+YnYgJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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