SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34c3a4526c3b6c2f0b3b40b5dd0dba7108ee701ea3b4dabb480388ecb551fb30' 
  AND token = 'qplo0rSAm06VAzbiKuHcOd+vlo91UDXb/v0IYkgDVQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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