SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '626a273ed4a6578f43829eb935656fd5b6dd0b910881560f275fba6bfba6c696' 
  AND token = 'hhn+XmzYcW627vBujHDw4g7ddCxfE73Fg/ew8kRIPXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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