SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '738923cb31a092e28a0dead745a1bc5df16813e857d631e0fb3807f1aa56c50c' 
  AND token = 'x6Z4IOU7BiBwC1EEOiI1erxU7VjOfD4ArLzdGjAPfcU=' 
  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"
    }
  }
}