SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91f433129b47c348934a1b7fe9ffa0962354b6fc6653fc790c0e7b94bb349f78' 
  AND token = 'tNg2mGfMp61LZ18rnfAVHh6CkKkXReP4EZi1X7j90so=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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