SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe6d1159ea94346fa6770a282ed96b0cc6f63f4a391a96e2d76b2f529edc4b35' 
  AND token = 'pwiuYvXYsLGw1Ph27GarDqL7ZtVBZDmMyt60NzwsF+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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