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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d878e1c81669f7aee13865e89be8cb81ab31d7c3de3b8f9d7daaf20d5625f00' 
  AND token = 'RV0UtCSXAXfySBC4WBX0L2BC5c3KqQ2+uCda3WtUb0M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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