SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5c389e77a8953d83b399f4594f80fda9be2910847670d94b9abba145e708bfe3' 
  AND token = 'auyzh/paUKi9oUAFZYXbjGIXyyPRk/8OP/946WAPGPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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