SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9902f4823821b1acc50f342d3178f067ca0767cb6e737a2bcf668a8984790d3' 
  AND token = '5RwolYjioEYEaIgXoCiyCKXFqcr91atFsNQhPcMQR5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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