SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd81be087b68b6c4d56acedc1a137ba7d06eda83eea80a4c6b36bea6a569137f' 
  AND token = '+DTAOWSgmUXJBh9r8Yy5jGipQ6AEtOEYiYXS+/viW3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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