SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7e25831b4d99077d24ae7a39f1bbd55d655fba9d850c7c396da0fa983347ba3' 
  AND token = '9usqvjV1jN+6J4pFpx0bCL4Sgfi42nMmKcAwYGuKwLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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