SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49736c34dbee42c55bdfc3073eccd3b3105b99383ae532d52d2001d7835b230c' 
  AND token = 'FpC28krgjLI9MkadtV5YRTUPU8GZ8Lmv1exFJM9982s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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