SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf3a5031961eb2ae7176dad39da3ca0ba14a768d17504d02ce51ecbb911f1a76' 
  AND token = '7gwlSGiZ5rCVzqlQBIGJ/wQXIHjR9mKDUXy4254b/Lc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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