SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '518aa36f85113cc2d417575f110c7f62c70f5229f926eb8a3c13a2c5f1752dcf' 
  AND token = 'QrL7GuSv2vTBqF+yiYvOElFqLxnKT5ybg3eJOpBLgL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00069

JSON explain

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