SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3c6afc34a2d75dd309793cb6ddc148f53be563618636de1a3f30598898c849e' 
  AND token = '1xBSfk780zV1v25LgHE5TsqmWSKXt95mMfxnn9hQIlU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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