SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3068d8dea0fcc86d9e609a3ed5a0315077e5848ad73d4a5eb27df58ac19fa4de' 
  AND token = 'w6ZWt7RWSdLEp9yGOxwhzZ2GQs1VVkeL91zpBGjRkSY=' 
  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"
    }
  }
}