SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3607073a40fedcda07b3aa1a76235f78e673cb032ee55d6af6eb722550afa98a' 
  AND token = 'AeHvmkxmY4u+Ch7K4Jgp6mOBQMwp/JXhGCbyWnhfRiw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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