SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ff51bf86c879036989e5d62e0d4606046e25f8f6a38be552763f364a7b55fcb' 
  AND token = '5Bbz06sfGR07n35iKEvgx2ZTZqgHN+g1zuMBw7rH/xw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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