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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a5304dfe8e384b4dc92dd3db325f52323b658b856b6222acd33256e52f928cc' 
  AND token = '5eXbBkXtTAbmvQAvv+AunzIfo/8L51GnSjq03XuRuN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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