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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d3ac90fb2eaa5aac93ff7550de6f62ce6af2f8db4b86de1adaeafa11cf48be6' 
  AND token = 'VLuKs8ZyteRlTjWI0NctJNzBYllsG13NAr/+DZd+kIA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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