SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ae168d310cbdf3f3eca72c9658adc76436a2104bf4d01d0f74cb5f11fba9ad6' 
  AND token = '7T/GwxiOW2KyZZQplS9sj0ym7O0X3AqkwFn274RrORA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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