SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa7214f20d20c0df5097be305a8e3afc1abccd9135855771f5cc4afcf78ea4db' 
  AND token = 'Ur79bCQOxHvFV7hZZ6h328zugijgSlpYBdqnZ+lnpZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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