SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b68d2d1337b16236dcad397727a2214f38b54cbf33675cc4c918e4e15a3b6d2' 
  AND token = '5nOoTBIqK2RoDUKdw0MHXhdWw6Fjb2JmGppwNclniDI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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