SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '574bd1fd538092ccf158bcea4ceb43538287b93332ca687655819fe5688d6690' 
  AND token = '46JqjJWiNJmYHeugY2WG5QfP/+wbrD7QSvzWj/vf1Aw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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