SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5299dfb5fe2bbf9383156d36949166f21717f6b0b9d95ca0d512e5d89078a02' 
  AND token = 'zScoUkmxiC4UID+pKYuxstZhOZA6kznbzl78eFn30aM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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