SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40bbe5fd2e2cb7d772f8159a65533cbc8fe367cefb0820de7e140a21c907744a' 
  AND token = 'gRQsDRwGBaWf+jpb6JZ6pvCBujuczgA45t20ah3lfVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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