SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e02d5b55646f29707342cc236ca337f7d8b308ec22d2f751bd536bb2807dc8d' 
  AND token = 'g9z3gRtTmfNwmMFehmugfEAPfTzHvHsNdGppICdukpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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