SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54666b99228cfe1456f30e569ab81f9eb353d0fe8df859dd2912a14d53e38672' 
  AND token = 'pd/jUxWMD3/n91vbIFVqLWF8OOrj212dvW0nal93omE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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