SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9543ecf6df637a87343e226a955b94ac3196bba42b46aa14d1d9103d0410f746' 
  AND token = 'H9Q/cUlIUTWBIOY+pPu63oshsw1xFzayOgYkeaDVrqE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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