SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29874c9ac006899d498af580fd9712239bb086eb04e9638ee1960c6bd60b9c5a' 
  AND token = 'mfTgc729UdRLSvgoaXYcrjDHkK2HsiqBhRuRL8FSeP0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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