SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '277ede11d377cdd3cb6c1a44963c62909eed8f8db68d680be584791c303da79d' 
  AND token = 'xLOkVnmi06X97aFOWRjgaqImIeMEWeq9oRNCVn4Cbz8=' 
  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"
    }
  }
}