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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2bf08b364de76100529d383c7384be56ccdc063a101d274c7457c321c12f558f' 
  AND token = 'DfIfZmpZRA1rltFJ8TQmyYblhHqt7La3/r6J+2UFwxk=' 
  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"
    }
  }
}