SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '24ef7f8a532294ba36984cd6b6b9177353212f768af37ccfe3250c17ebf4167c' 
  AND token = '3xxcM+GOX7zqWvEhkmR1465ugSwOGsNc6hgLQBZXRCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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