SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '702796b4cae62bc1eb649b67e81a08893c81d79966a474d7f2690cf3fee6219c' 
  AND token = 'dHEaoHiWL/fn0oP/vyIfpzREjBC4IwmKIJwrTEgXwks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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