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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4761bc68ad52e6ee7bbd8c6cc728c2687c8e1e1d6c634aea49d03e92d1b6cc47' 
  AND token = 'HP6S8PY89IeTirSQKJoykFRPzb+3pzAW/ntI+M2Hrwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}