SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42d9f620a072c110a19ce9544a85f001450a525f56276bc38a786b4b03ab3708' 
  AND token = '9rJMkDPIydzBy5qvJVYwr/ygOZu4Ev+5bZl1R+UW+0w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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