SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83e2f08c35a9fbdfea25396fc054690bbe7d7f9f2560c281ae664b70753ddccd' 
  AND token = 'VC3cxLaJfEzhxK1Qkp/9m0AK+VvlCo2nLWnKHO/+9zY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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