SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbe93c8674596bbf080e7abbb6603601565ebf9e567573d48bf65f0ef8750fcb' 
  AND token = 'tN6bNQwPmKbfQChIoEgv+Hq9qLj7ipXc/VeAfHzg+Co=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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