SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de83d1b3c9046c48ffb0a45408e27cf98caf731aa486fc4a133bab9bcdcc532e' 
  AND token = 'yHC+TPij9g75tWYZqA2XJwGy9RkQz4QMhV6AYQs94gY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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