SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '824bf436cd808c4783fd6e578e7c9223123639d021725d81ce7de069cd36888c' 
  AND token = 'PHgzskLmIzdOsrZngY5xNgv3f+KmKXu/M4rQG1OFMD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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