SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7724cbcc7b506160cad73c4afca8a216bea788fd19d046c429f359c8b1453299' 
  AND token = 'wjl+p9lFpmLE2CVzsAnlA8AZQ+X59mfQT68fHh/+yFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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