SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '4f62b5cb37a32b750e123948faccfcb742f9a295669920748426a075fd0fad92' 
  AND token = '42hMppv2DW7+7eVoiuRDNpJYwiVI3jZg/UqpPtd+LXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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