SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0b96ad0b9471167c2487f2a5bbf7abed21b3ca3969594624367393b3b1d50cbe' 
  AND token = 'trKj7ISfVp9DHQSpW3bwgfo3yFbECfV996iOwK5alxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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