SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7fc2fbf432609d6eae263fb2b5b29cc76eac3708caa1370c229d2f25771da900' 
  AND token = 'x0PjRh9/nkgxJV8ncBAQ/Vx2aqW9LrjzHyzrJUPScE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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