SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52a719b39dfbd887d1b1b64a84405946f8c9d27a0a3f4aecb88d2665de4d9e63' 
  AND token = 'a8nJR42k06txAzI6ewQrmrmeuhUhiCBCqLE4zvaSaKA=' 
  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"
    }
  }
}