SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '206bf5f321fac5d7618d75f7a0036529dbdf2a0f36354b88ed0986acc125c132' 
  AND token = '/6/lJPdlFlHNByYoWaKuw+ROq6HQBxOnowsAFi3mx50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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