SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fe1285751f50126db5765831c2d6e36d4c2a44783e9d6681dcea00c81fd00ac' 
  AND token = 'L1UQ85rDHgBGw0B+0tXknjQXfPNOTBHE9EsQjL/DRlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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