SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4ab1d79626c43a79b777e5ffa95583e84435b5bcf0c949001f7a73853d1e1e5' 
  AND token = 'iR/gMVzhvYswUdD1LLTc5Qghw1fTNWc4IAGujZ92zLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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