SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79c3eebdc3eede6e7dd13f8a56d9f88207a31134b9fb64d72e8b23fdd37a28a7' 
  AND token = 'kxZIRIvNoaaganzGF+zSdqUkWOUZhmW+CF3J5d/1uYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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