SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3df050ba4f57d005826ddf6c5547331e46f034847fc2b2a348d63e2257b5d3ff' 
  AND token = '4vLMtcXqlmTmcbCPheKFZMjlaSh6WBK3LYwvrRk0g5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}