SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3516d0b7313f178a9c3a204c104c3a57046e7a1b688d7f3115c9d5f7d83876ee' 
  AND token = '/d/bJGaV7jRmpP6lzGzYzsa1TrRADMPuLUkwgJk2lI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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