SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23bdc07f0ce9c7e2feda1a26ddb3d4c39cfa780e7a353e2c0413ac7f84a7a921' 
  AND token = 'N2x6SJUmQHastrw6wkteikLnfaOY63T1A93UrK6NiIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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