SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4437d9dcc6cc3eb2549feeecd046053617d0a15e1dd19299f4574ba512f4acbe' 
  AND token = 'fs/V3DYAVacfbKbEFBAmvoDyzJU750h1VKmazL2ZRnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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