SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f21cac1e2ef82bf83a9ea91cd237d570af0f6017c93c92756b0658a5f46715ee' 
  AND token = 'XLDl6Bnw1dnbjI6MVesj9lrcnKZzmO6zFQGV03+spog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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