SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3b8bb9ae4dfadc5ed96b88a254c62615b0206bda4c9346957508f32db3819f7' 
  AND token = 'FtljknpgWrIxld6gEmRxXKVBugO+MZMHlbxkGRYR3Pg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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