SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4657a930c73e7fc851eacaa5d98e231af236df7f4d2f24fcfe85a793995cadb8' 
  AND token = 'MQenWLVKJ+Kyu0jg8iGOoygDjKkWM3oRJO5HhWIL3hI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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