SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb79f66b2e9c31eee12396b13f96c427352f476b45d95ed06bf897b07b6fe7bc' 
  AND token = '/2bejWjGfUhVotPHcc9glKIeLvXxL5BRTUDqzy84vwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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