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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f8c032b6cfde9a8b5ca3a14155c469986215a89448a5554a08f38d4a278ee14' 
  AND token = 'vZMqx6DybcUKfA9XVDNQS+azfMkfH98qfXseID5LSoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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