SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6f8e0616825d9593f5914f88e22d729fbef6f4bdb33e20068d6fc49285c70793' 
  AND token = 'adBNAXelGOQCKDjie6tyMDZOsrP/J4qsg3uQZ2wZokk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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