SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99cf5c73bf2bc53385f7d4aeb654da1f14b9ff537b187f8b3559ad9766b01ed6' 
  AND token = 'lXgPBYhgx5pT0AoZoTMkD3vQvC+3OrPzExZ11R7qfBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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