SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15e09d38c573ee156c3b634aca4b7bb6f1fd453eb2fe8218cc17bd60845f50c5' 
  AND token = 'Df8t+Ff41SgKTXiXSKPmYm4plDE69ZjD5G9vPviNd64=' 
  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"
    }
  }
}