SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '2451570be4f49b38e7600b08e1557e117e5be82f7aa114e8a5b91ad1a057bf9e' 
  AND token = '51bOpqPCMjmTU46+UxyN/55e4OkNfbPsYpo7GtC126c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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