SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a23af15f8a09b857cc618420dcabd509986692a9f24230349b97a26946635c5' 
  AND token = 'r+J0xgg3yTHoJp2h7UHr1WHOzqmPVzYvJTUTtiPC8Ug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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