SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ed9ea33095c9be9115e6a1c6fd5c307f018d588dd438efeab3adc1cf2c68c41' 
  AND token = 'zLMXg9gEARX94EJz4bAVkOmg2ovZYj8/j1+G9bfYFtU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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