SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc7c85f41918632d247b535bb51393f1d168b5c7c142ee641f5e8faa541e563b' 
  AND token = 'Up3nwdyOkli1cDmqH8T4JtTQ39clhRPPiakpnB5tQKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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