SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aee8978bd02e8bfc9ef1f64cac2a507868a4121d39be6a9753e2e969536dc1c5' 
  AND token = 'LgtyKGSqWH334vNEnwXKiA/D+bE25CVRk8bdp9yuWME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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