SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd8868c69852c51894573fdfdd778e90f929c386900c326af482c45b6d10423b' 
  AND token = 'tbl/fcYTTycXjuAJGOAzU/emDFsmc2Tzxjsfef3rwmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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