SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '90c50deda8ab67f402e37d1bbaaa870104e73230b5c867b2e032d3f35cded256' 
  AND token = '59HqNKsdFS6IVBYyppunoW7vguXqLBOfZGkTIjEugb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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