SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21148d8bba6dda82e2cbcdfe5f18c883245b10fd2ca5e5319e81148074af4bab' 
  AND token = 'ZdqtEzkaYOyNQqtj4cCTWN4OJtRd6XEGUEcaIGDA3Vg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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