SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '687669e8ef699fdac392a917c625167dd4f24bb25e04f4d89795a85e47b60886' 
  AND token = 'khROYunwOGG/B+VtrtiMeS/ZGkPeZSM9qeTG9FKQilI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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