SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '487903acab157a32b8d100a23f4a73fc0c1d4f2bc3e537f12130da4d8ecdbc28' 
  AND token = '+3ENOkjbXq8LkrOyctNBzBVgBMbTUyc8j9qwBmvudoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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