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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2161dc36a6c1e20453364b6d2b8f54b0fc27a3c4fa6ce7f364cd7f45715b2e3c' 
  AND token = 'HcAKbD8Xa2JMy2fdsQKluUOZKlE8LsrvEZ5y00UJbUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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