SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0282fd1dd82d51776570d3737c9e05aaf0197af3c4f1009e4d3825d2d7518bd' 
  AND token = 'ARSj4BqM5geBw+Ku4AFPyw6gkDz7YVTeZiLxAZLvQRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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