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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb1dff7cb33e90d14007ae26355d6ae90d42eb4f7519398df00768c841c4c211' 
  AND token = 'S8phak3msiyN/IOvTgepfJjO/HMHtH3mgVxHr2TcHk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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