SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc3d5d8d90b73e5849aeffa68becf8436b33aedb4ec783d6751f0a1b9ff520db' 
  AND token = 'fIv4oIrnhgcZhUgYHRT9aM6f/GFQ24SKHTPN2hrevOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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