SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d94497787e4208c63ee5a2f1a7df312b56649a2473a5bbe2ac518f329df8a6a' 
  AND token = '/SuHGUHYKtiz3tFHuvClCCOcsIvihGprhnn1uU8l2hg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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