SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fc406cc42908073fc41cadfd9b54f527d04015b16ae046d73e557be9dbe3720' 
  AND token = 'OXaEXZzPEMtO/nOYlDPe2bKLBnR4YMgYF7AieYBjRDc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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