SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5947b5b333dba53430755a930bb01355b50e1db544e326e5c61e2b1003e776a8' 
  AND token = 'L2jVd7A+a7k/eS+PsrPgIeXZaS8UVpcnXrakey5YaNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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