SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6259ceaf03ec42b00bac39c2bf87479e090b939c296260b55bde6378321e2a8e' 
  AND token = '6xlkoGXXH3GqWelF0LLWntD08VPrsPIcz6Od9bk+1dM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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