SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6c6f79135727c8960519d9ad5db3763df88b39c99916d5b4c40934ef64570c1' 
  AND token = '9apF8tZ6n5xGOjF3nq3GC19x6wILhC9VA5sDBLaEENI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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