SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5eb30780484809323bc303a575b70351f486254a7c208df0f62125b21e9a58dd' 
  AND token = 'USZsjMRIET7Y4Ep066DSBmfRGUYtRXwwjCLmhxBIqhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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