SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c3efd1eaea7d1bcfab2a24bfb1ca458cde769a9c0a6b935814e7489d23cb110' 
  AND token = 'FzzVWwKAchrgpfZsMrUey6M6ZWQ/NqyqOMXXK3G8v8M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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