SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b93f4263b7b0279b6b2f3ff2f0676d38cf56d5e51f74a0ab16d9b0fd93537ea' 
  AND token = 'RvQECHVtPOhtp48sf7X9lHbF4zjDl02P7+gYKz1zZnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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