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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99a9d618ff4f745d4e61a946c2b60b83da8bf0edd7ada74ff9c86e56defd48cf' 
  AND token = 'ci5X/v4lZ9ZvlAKyi2NDTe5qY3gQK3O6WQDwRqUwJQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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