SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b46d98cd4dcf16c09bb507adafbec128ab3012aa35427a3f8a6c9d8cb2921868' 
  AND token = 'D2gYQSOxXwKGCBKd6ajDevzTlukF+tLVTR6v9thAW+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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