SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '48fb8f9b0763795f4f2e5887f8140e39579dcdba3135b67e6e98efdafc6c3df9' 
  AND token = 'K6IwB2NQszuMwWKPBTRRDvhgdzEQLjSajAZZzjex7pY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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