SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fbe49c44e4a7173d55d2684567675662cf266897436a8a7a7f161e2646c42a4' 
  AND token = '9y/DEWAL921hpZqxOVbAj+jk/8zIzHdgfdlKk3w1R9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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