SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e2fe7b9b6884eab02b2c1f0a173db4437c3df9b96cf60a8bfe93bd68b415a83' 
  AND token = 'NuZmXIneuKghAMUBW8MTyJLZ9OlRNoMfJZJ9z5XCsXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}