SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '820e7676953c3dbd365309e571d9729d5c63134a44b215bd41610b0476a96693' 
  AND token = '4DN9l3QYP5MJdMfVDebjT/aUyJbKtownysxEDCW6NrA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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