SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '495add8e721c296906bb630976424b6bb91ecc15d48b8dca4d0c2964a3e646cd' 
  AND token = 'MDuvSvm+B8XcXjjgJjckn8ehW9PjiSKtC9O+5eI6RR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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