SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dbe1af6061b893b4137ff996b2d8c755b11e2eb3981f27c01a7f444703246a4' 
  AND token = 'EJHCWlHhUlWaSQpesCRe7XA6bC3UPfsoiuZzQWgAjSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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