SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b43bf07a7f7be4475bf0432f02f8da621cd0b4bf4bb4c6acb79fa82cf208e6f6' 
  AND token = 'wRzu/BZ5VSkTnuzjlxTIcFw/sV4w6n4W8scI6y1hXKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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