SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8ca874c0d73a61ae3c498d7d17405ad9ba557634a6826e1c8567a39611bd7de' 
  AND token = '5csXmiEvQnDeR0eAaxf5HgSu0brrBrM7ekGYUEBByjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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