SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '623b1b57f018f3c557ed60736422f5d90df0d0517007a48806a8892ed9d72b41' 
  AND token = 'BcBzGYU6ceEbKaprcJCWLNUftdyzrbjgjjkZvvl8wLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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