SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a6bc669f89783e1500ce230ce2235bb24fd5565356dfd62712fc41ea13e27a3' 
  AND token = 'hhTinU0lnQK6a1r2RnklvHpMRDXygPAAoodXjHZ+nsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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