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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '321e9b99b593c96dd3ab2bf73dee5dd72b46bbf721cdc2e335eaba3f0ac75b9b' 
  AND token = 'oojQ6ittsr6d78uGwqBbOJFGBz09rs25bBEjXEb49MA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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