SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74683aa92645e089a1efaecf5864b1cbcdace58d47a4105b8015bd565130a8df' 
  AND token = 'cbjmYkGk2BlRl2GuXzFzmAAXMiBAJoW8BXIVJprshbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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