SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4eaca7dca99466a13640381c46f523d08ddec4c4e25493325577d1de2eca5e55' 
  AND token = '/3YNlUfmqeMjCbuhaMgusCR2vOfeRwARrkWHnznnH78=' 
  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"
    }
  }
}