SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfe9b6ec52a4aa24c7cdfcf6a517f6b219d8143500a71421d7e0ffd72048d660' 
  AND token = 'pZCCWyIBPtw+5ZHKu8OCBOZQVH0rG8vCvmZitxRAdHM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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