SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fba0cb87ca78fd439bbe08fda442ad7d9504ffee0c5bff3af45bb440e5e5d75a' 
  AND token = 'jFy6HT/UZqG3a3ObIWVmyNXCp+wenZLX3B/RYWevCh0=' 
  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"
    }
  }
}