SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fa98c1f7de54a59a31e64e73b52c77679271db3a05acdaf2e39cc90b3437097' 
  AND token = '7vEG+IWPb4NmwNjv9Ww6vsLOOSPmZ42DtKe3bmBxYMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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