SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8294d31f5b34681b41a3de5cc9941e775e259181342926e4341d5797b964c0cd' 
  AND token = 't7pFZEGRoB7eJYcDM+eoWOpu+xXBnlcoXl3ftBq3zaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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