SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76f09e4003f9a4561a6eb9811282b499c8c7d6b5a74026b985b82a093df0b371' 
  AND token = '/yhJ2MHwywGOSR1UbzmIb7bTMp2oens462twxfxGdOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}