SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4edd36d1457efe3a34571a9dfe2f60c7e23bc9e0143930772561cf99b809cccd' 
  AND token = 'UB8Q3RuaHvWXAhF0Gvf/Anhs+XwYLY6zvrkqSBvlfBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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