SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37ec28a4d8101b12b770338e6bd4cda93121d88e5b8855a28b4728575b6b0545' 
  AND token = 'buiyVwLydSRTFNae90AQKLwLzcUWgTkqncQd9kjzodA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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